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  • 1. Abadei, S.
    et al.
    Gevorgian, S.
    Cho, C. R.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Low-frequency and microwave performances of laser-ablated epitaxial Na0.5K0.5NbO3 films on high-resistivity SiO2/Si substrates2002In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 91, no 4, p. 2267-2276Article in journal (Refereed)
    Abstract [en]

    The dielectric properties of laser-ablated 0.5-mum-thick c-axis epitaxial Na0.5K0.5NbO3 (NKN) films on high-resistivity (>7.7 kOmega cm) silicon SiO2/Si substrates are studied experimentally in the temperature interval of 30-320 K and at frequencies of 1.0 MHz-40 GHz. The films are grown by laser ablation from a stoichiometric target. For the measurements, planar 0.5-mum-thick gold electrodes (interdigital and straight slot) are photolithography defined on the top surface of NKN films. The slot width between the electrodes is 2.0 or 4.0 mum. At low frequencies (f<1.0 GHz), the structure performance is that of a typical metal-dielectric-semiconductor type, where two of this type of capacitor are connected back to back. At these frequencies, the large change in the capacitance (more than 10 times at 1.0 MHz), due to the applied dc field, is mainly due to the changes in depletion layer thickness at the surface of silicon. The associated losses are also large, tan delta>1. At microwave frequencies (f>10 GHz), the voltage dependence of the capacitance is given by the NKN film. More than a 13% capacitance change at 40 V dc bias and a Q factor of more than 15 are observed at 40 GHz, which make the structure useful for applications in electrically tunable millimeter-wave devices.

  • 2. Abadei, S.
    et al.
    Gevorgian, S.
    Cho, C. R.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Andreasson, J.
    Lindback, T.
    DC field dependent properties of Na0.5K0.5NbO3/SiO2/Si structures at millimeter-wave frequencies2001In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 78, no 13, p. 1900-1902Article in journal (Refereed)
    Abstract [en]

    Dielectric properties of laser-ablated 0.5-mum-thick c-axis epitaxial Na0.5K0.5NbO3 films on high-resistivity (7.7 Omega cm) silicon SiO2/Si substrate are studied experimentally at frequencies up to 40 GHz. For measurements, planar 0.5-mum-thick gold electrodes (interdigital and straight slot) are photolithography defined on the top surface of Na0.5K0.5NbO3 films. The slot width between the electrodes is 2 or 4 mum. 13% capacitance change at 40 V dc bias and Q factor more than 15 are observed at 40 GHz, which makes the structure useful for applications in electrically tunable millimeter-wave devices.

  • 3. Achanta, S.
    et al.
    Feuerbacher, M.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Ye, X.
    Celis, J. -P
    On the mechanical and tribological behavior of Al3Mg2 complex metallic alloys as bulk material and as coating2010In: Intermetallics (Barking), ISSN 0966-9795, E-ISSN 1879-0216, Vol. 18, no 11, p. 2096-2104Article in journal (Refereed)
    Abstract [en]

    New materials with tunable physical, mechanical, chemical, and thermal properties are attractive for many applications and stand as prospective substitutes for the existing engineering materials. In that respect, complex metallic alloys (CMA) have recently demonstrated promising traits where a myriad of physical, mechanical, chemical properties can be obtained by altering the structure. CMA's have a large crystal size with thousands of atoms per unit cell. In this work, some mechanical properties and tribological behavior of Al3Mg2 based CMA are discussed. The surface characterization, deformation mode, mechanical and tribological properties of bulk and thin film Al3Mg2 materials are investigated, and compared with existing engineering materials. The results revealed a contrasting tribological behavior of Al3Mg2 when used as either bulk material or as coating. Al3Mg2 coatings act as a low friction solid lubricant under certain conditions, with a coefficient of friction comparable to that of diamond-like carbon coatings. It is suggested that the quasi-crystalline nature of Al3Mg2-coatings renders the surface stiff and that the characteristics of the wear debris generated are responsible for the low friction behavior.

  • 4. Adachi, N.
    et al.
    Denysenkov, V. P.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Okuda, T.
    Epitaxial Bi3Fe5O12(001) films grown by pulsed laser deposition and reactive ion beam sputtering techniques2000In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 88, no 5, p. 2734-2739Article in journal (Refereed)
    Abstract [en]

    We report on processing and comparative characterization of epitaxial Bi3Fe5O12 (BIG) films grown onto Gd-3(ScGa)(5)O-12[GSGG,(001)] single crystal using pulsed laser deposition (PLD) and reactive ion beam sputtering (RIBS) techniques. A very high deposition rate of about 0.8 mu m/h has been achieved in the PLD process. Comprehensive x-ray diffraction analyses reveal epitaxial quality both of the films: they are single phase, exclusively (001) oriented, the full width at half maximum of the rocking curve of (004) Bragg reflection is 0.06 deg for PLD and 0.05 deg for RIBS film, strongly in-plane textured with cube-on-cube film-to-substrate epitaxial relationship. Saturation magnetization 4 pi M-s and Faraday rotation at 635 nm were found to be 1400 Gs and -7.8 deg/mu m in PLD-BIG, and 1200 Gs and -6.9 deg/mu m in RIBS-BIG. Ferromagnetic resonance (FMR) measurements performed at 9.25 GHz yielded the gyromagnetic ratio gamma=1.797x10(7) l/s Oe, 1.826x10(7) l/s Oe; the constants of uniaxial magnetic anisotropy were K-u(*)=-8.66x10(4) erg/cm(3), -8.60x10(4) erg/cm(3); the cubic magnetic anisotropy K-1=-2.7x10(3) erg/cm(3),-3.8x10(3) erg/cm(3); and the FMR linewidth Delta H=25 and 34 Oe for PLD and RIBS films correspondingly. High Faraday rotation, low microwave loss, and low coercive field less than or equal to 40 Oe of BIG/GSGG(001) films promise their use in integrated magneto-optic applications.

  • 5. Adachi, N.
    et al.
    Okuda, T.
    Denysenkov, Vasyl
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Jalali-Roudsar, Amir
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Magnetic properties of single crystal film Bi3Fe5O12 prepared onto Sm3(Sc, Ga)5O12(111)2002In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 242, no Part 2, p. 775-777Article in journal (Refereed)
    Abstract [en]

    Magnetic properties of single crystal Bi3Fe5O12 has been investigated in the temperature range between 2 and 670K. The Sm3(Sc,Ga)5O12 wafer has been used for substrates. Due to the small contribution of the substrate's magnetization, the film's magnetization can be clearly estimated to be 2040G (0K) and the Curie temperature has been estimated to be around 650K.

  • 6.
    Ansari, Nazanin
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Multicolor filter all-garnet magneto-optical photonic crystals2012In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, no 17, p. 3552-3554Article in journal (Refereed)
    Abstract [en]

    We demonstrate a multicolor optical filter and isolator based on a double-cavity magneto-optical (MO) photonic crystal. Being grown as a heteroepitaxial all-garnet multilayer, it compromises a strong MO response and high optical transmittance. Low-loss, high Faraday rotation passbands as well as strong light rejection within the stop band were achieved by optimization of distance between cavities and repetition number of distributed Bragg reflectors.

  • 7. Artemov, A. N.
    et al.
    Drobotko, V. F.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khokhlov, V. A.
    Kosse, A. I.
    Levchenko, G. G.
    Medvedev, Y. V.
    Prokhorov, A. Y.
    Large effect of thermal processes on the susceptibility of YBCO film with transport current2004In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 403, no 3, p. 157-162Article in journal (Refereed)
    Abstract [en]

    The response of YBCO film with transport current to the weak alternating magnetic field was studied. The hysteresis of the temperature dependences of the response measured under cooling and heating was revealed. The qualitative explanation of this phenomenon is proposed. It is based on the fact that under certain conditions the superconductor with transport current has two steady states. It is found that the hysteresis arises only if transport current exceeds some finite value I-0.

  • 8. Belotelov, V. I.
    et al.
    Kreilkamp, L. E.
    Akimov, I. A.
    Kalish, A. N.
    Bykov, D. A.
    Kasture, S.
    Yallapragada, V. J.
    Gopal, Achanta Venu
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Khartsev, Sergiy I.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Nur-E-Alam, M.
    Vasiliev, M.
    Doskolovich, L. L.
    Yakovlev, D. R.
    Alameh, K.
    Zvezdin, A. K.
    Bayer, M.
    Plasmon-mediated magneto-optical transparency2013In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 4, p. 2128-Article in journal (Refereed)
    Abstract [en]

    Magnetic field control of light is among the most intriguing methods for modulation of light intensity and polarization on sub-nanosecond timescales. The implementation in nanostructured hybrid materials provides a remarkable increase of magneto-optical effects. However, so far only the enhancement of already known effects has been demonstrated in such materials. Here we postulate a novel magneto-optical phenomenon that originates solely from suitably designed nanostructured metal-dielectric material, the so-called magneto-plasmonic crystal. In this material, an incident light excites coupled plasmonic oscillations and a waveguide mode. An in-plane magnetic field allows excitation of an orthogonally polarized waveguide mode that modifies optical spectrum of the magneto-plasmonic crystal and increases its transparency. The experimentally achieved light intensity modulation reaches 24%. As the effect can potentially exceed 100%, it may have great importance for applied nanophotonics. Further, the effect allows manipulating and exciting waveguide modes by a magnetic field and light of proper polarization.

  • 9. Belotelov, V. I.
    et al.
    Kreilkamp, L. E.
    Kalish, A. N.
    Akimov, I. A.
    Bykov, D. A.
    Kasture, S.
    Yallapragada, V. J.
    Gopal, A. V.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Khartsev, Sergiy I.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Nur-E-Alam, M.
    Vasiliev, M.
    Doskolovich, L. L.
    Yakovlev, D. R.
    Alameh, K.
    Zvezdin, A. K.
    Bayer, M.
    Magnetophotonic intensity effects in hybrid metal-dielectric structures2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, no 4, p. 045118-Article in journal (Refereed)
    Abstract [en]

    The magneto-optical properties of a hybrid metal-dielectric structure consisting of a one-dimensional gold grating on top of a magnetic waveguide layer are studied experimentally and theoretically. It is demonstrated that a magnetic field applied in the longitudinal configuration (in the plane of the magnetic film and perpendicular to the slits in the gold grating) to the metal-dielectric structure modifies the field distribution of the optical modes and thus changes the mode excitation conditions. In the optical far field, this manifests in the alteration of the optical transmittance or reflectance when the structure becomes magnetized. This magneto-optical effect is shown to represent a novel class of effects related to the magnetic-field-induced modification of the Bloch modes of the periodic hybrid structure. That is why we define this effect as "longitudinal magnetophotonic intensity effect" (LMPIE). The LMPIE has two contributions, odd and even in magnetization. While the even LMPIE is maximal for the light polarized perpendicular to the grating slits (TM) and minimal for the orthogonal polarization (TE), the odd LMPIE takes maximum values at some intermediate polarization and vanishes for pure TM and TE polarizations. Two principal modes of the magnetic layer - TM and TE - acquire in the longitudinal magnetic field additional field components and thus turn into quasi-TM and quasi-TE modes, respectively. The largest LMPIE is observed for excitation of the antisymmetrical quasi-TE mode by TM-polarized light. The value of the LMPIE measured for the plasmonic structure with a magnetic film of Bi2Dy1Fe4Ga1O12 composition is about 1% for the even effect and 2% for the odd one. However, the plasmonic structure with a magnetic film with a higher concentration of bismuth (Bi2.97Er0.03Fe4Al0.5Ga0.5O12) gives significantly larger LMPIE: even LMPIE reaches 24% and odd LMPIE is 9%. Enhancement of the magneto-optical figure of merit (defined as the ratio of the specific Faraday angle of a magnetic film to its absorption coefficient) of the magnetic films potentially causes the even LMPIE to exceed 100% as is predicted by calculations. Thus, the nanostructured material described here may be considered as an ultrafast magnetophotonic light valve.

  • 10.
    Blomqvist, Mats
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Electro-optic effect in ferroelectric Na0.5K0.5NbO3 thin films on oxide substrates2006In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 80, no 1, p. 97-106Article in journal (Refereed)
    Abstract [en]

    We have deposited Na0.5NbO3 (NKN) films oil single crystal Al2O3(1 (1) under bar 02) and SrTiO3(001) substrates using rf-magnetron sputtering of a stoichiometric, high-density ceramic target. Using x-ray diffraction it was confirmed that NKN grows preferentially c-axis oriented on sapphire substrate and epitaxially oil the perovskite SrTiO3(001) substrate. Electro-optical (EO) properties were measured in visible light through a transverse method. With an applied dc field up to 20 kV/cm, the effective linear EO response was determined to r(eff) = 28 pm/V for NKN/Al2O3 and r(eff) = I I pm/V for NKN/SrTiO3, where a superlinear dependence was observed.

  • 11.
    Blomqvist, Mats
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Electrooptic ferroelectric Na0.5K0.5NbO3 films2005In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 17, no 8, p. 1638-1640Article in journal (Refereed)
    Abstract [en]

    We report on waveguiding and electrooptic properties of epitaxial Na0.5K0.5NbO3 films grown by radio-frequency magnetron sputtering on Al2O3 (1102) single crystal substrates. High optical waveguiding performance has been demonstrated in infrared and visible light. The in-plane electrooptic effect has been recorded in transmission using a transverse geometry. At dc fields, the effective linear electrooptic coefficient was determined to 28 pm/V, which is promising for modulator applications.

  • 12.
    Blomqvist, Mats
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Visible and IR light waveguiding in ferroelectric Na0.5K0.5NbO3 thin films2005In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 69, p. 277-286Article in journal (Refereed)
    Abstract [en]

    High-quality ferroelectric thin films are attractive materials for integrated optics applications including electro-optic waveguide modulators and frequency doubling secondharmonic generators. Several fefroelectric thin film materials, such as BaTiO3, KNbO3, LiNbO3, and (Pb,La)(ZrTi)O-3, have been investigated regarding their optical and waveguiding properties. Recently the first results on waveguiding in ferroelectric Na0.5K0.5NbO3 (NKN) thin films were presented. Perovskite NKN films have previously been investigated as electrically tunable material for low loss rf and microwave applications. Na0.5K0.5NbO3 thin films of thickness 0.5-1.0 mum have been deposited on Nd:YAlO3(001) and Al2O3(0112) substrates using rf-magnetron sputtering of a stoichiometric, high-density ceramic target. X-ray diffraction measurements confirmed films grown highly (00l) oriented on the perovskite Nd:YAlO3 substrate and preferentially c-axis oriented on the single crystal r-cut sapphire substrate. Optical and waveguiding properties were characterized using a Metricon 2010 prism-coupling apparatus with a rutile prism. Dark-line spectra were obtained at visible light (lambda = 632.8 nm) as well as at infrared optical communication wavelengths, lambda = 1319 nm and lambda = 1549 nm, in both transverse electric (TE) and transverse magnetic (TM) polarizations. Sharp dips corresponding to waveguide propagation modes in the thin film layers where observed for both substrates. The calculated refractive index values and corresponding birefringence (Deltan = n(TM) - n(TE) = n(e) - n(o)) as a function of wavelength has been compared. Generally a larger birefringence is observed for the NKN film on Nd:YAlO3, which is in agreement with the larger degree of preferential c-axis orientation measured by XRD.

  • 13.
    Blomqvist, Mats
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Petraru, Adrian
    Institute of Thin Films and Interfaces, Section: Ion Technology, Forschungzentrum Jülich.
    Rf sputtered Na0.5K0.5NbO3 films on oxide substrates as optical waveguiding material2003In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 54, p. 631-640Article in journal (Refereed)
    Abstract [en]

    Highly crystalline Na0.5K0.5NbO3 (NKN) thin films of 1-2 mum thickness were deposited by rf-magnetron sputtering of a stoichiometric, ceramic target on single crystal LaAlO3 (001) and Al2O3 (01 (1) under bar2) substrates. X-ray diffraction measurements revealed epitaxial quality of NKN/LaAlO3 film structures, whereas NKN films on sapphire substrates were found to be preferentially c -axis oriented. A prism-coupling technique was used to characterize optical and waveguiding properties. A bright-line spectrum at lambda = 632.8 nm, revealed sharp peaks, corresponding to transverse magnetic (TM) and electric (TE) waveguide propagation modes in NKN/LaAlO3 and NKN/Al2O3 thin films. Using a least mean square fit the refractive index for the films and film thickness were calculated. The extraordinary and ordinary refractive indices were determined to n(e) = 2.207 +/- 0.002 and n(o) = 2.261 +/- 0.002, and n(e) = 2.216 +/- 0.002 and n(o) = 2.247 +/- 0.002 at lambda = 632.8 nm for 2.0 mum thick NKN films on LaAlO3 and Al2O3 , respectively. This corresponds to a birefringence Deltan = n(e) - n(o) = -0.054 +/- 0.003 and Deltan = -0.031 +/- 0.003 in the films, where the larger Deltan for the NKN/LaAlO3 structure can be explained by the superior crystalline quality compared to NKN/Al2O3 . Atomic force microscopy images of the film surfaces revealed rms roughnesses of 2.5 nm and 8.0 nm for 1.0-mum thick NKN/LaAlO3 and NKN/Al2O3 films, respectively. We believe surface scattering is one of the main sources of waveguide losses in the thin films.

  • 14.
    Blomqvist, Mats
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Petraru, Adrian
    Inst. of Thin Films and Interfaces, Section: Ion Technology, Forschungszentrum Jülich.
    Buchal, Christoph
    Inst. of Thin Films and Interfaces, Section: Ion Technology, Forschungszentrum Jülich.
    Optical waveguiding in magnetron-sputtered Na0.5K0.5NbO3 thin films on sapphire substrates2003In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 82, no 3, p. 439-441Article in journal (Refereed)
    Abstract [en]

    Preferentially oriented perovskite-structured Na0.5K0.5NbO3 (NKN) thin films have been deposited on hexagonal Al2O3(01 (1) under bar2) substrates using rf magnetron sputtering of a stoichiometric, high-density, ceramic target. Structural and film surface properties were measured using x-ray diffraction and atomic force microscopy, respectively. Optical and waveguiding properties were characterized using a prism-coupling technique. We observed sharp and distinguishable TM and TE propagation modes and measured the refractive index of NKN thin films of different thicknesses. The ordinary and extraordinary refractive indices were calculated to be n(o)=2.247+/-0.002 and n(e)=2.216+/-0.002 for a 2.0-mum-thick film at 632.8 nm. This implies a birefringence Deltan=n(e)-n(o)=-0.031+/-0.002 in the film. These first results show the potential use of rf-sputtered NKN films as an electro-optical active material.

  • 15.
    Blomqvist, Mats
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Koh, Jung-Hyuk
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Rf-magnetron sputtered ferroelectric (Na,K)NbO3 films2002In: Proceedings of the 13th IEEE International Symposium on Applications of Ferroelectronics / [ed] White, G.; Tsurumi, T., 2002, p. 195-198Conference paper (Refereed)
    Abstract [en]

    Sodium potassium niobate (Na,K)NbO3 (NKN) thin films were grown by rf-magnetron sputtering from stoichiometric Na0.5K0.5NbO3 target on LaAlO3 (LAO) single crystals and polycrystalline Pt80Ir20 (PtIr) substrates. NKN films on polycrystalline PtIr substrates were found to be preferentially (004 oriented while XRD measurements reveal epitaxial quality of NKN/LaAlO3 film structures. The ferroelectric state in NKN/PtIr films at room temperature is indicated by polarization loops with polarization as high as 33.4 muC/cm(2) at 700 kV/crn, remnant polarization of 9.9 muC/cm(2), and coercive field of 91 kV/cm. I-V characteristics of vertical Au/NKN/PtIr capacitive cells and planar Au/NKN/LAO interdigital capacitors (IDCs) showed very good insulating properties. For NKN IDC the leakage current density was in the order of 30 nA/cm(2) at 400 kV/cm. Rf dielectric spectroscopy demonstrates low loss, low frequency dispersion, and high voltage tunability both for vertical Au/NKN/PtIr and planar interdigital Au/NKN/LAO capacitors.

  • 16.
    Blomqvist, Mats
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Koh, Jung-Hyuk
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Andréasson, Johanna
    Department of Materials and Manufacturing Engineering, Luleå University of Technology.
    High-performance epitaxial Na0.5K0.5NbO3 thin films by magnetron sputtering2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 2, p. 337-339Article in journal (Refereed)
    Abstract [en]

    Epitaxial Na0.5K0.5NbO3 (NKN) thin films have been grown on LaAlO3 substrates by rf magnetron sputtering of a stoichiometric, high-density, ceramic target. X-ray diffraction analysis showed c-axis oriented cube-on-cube growth. Micrometer size interdigital capacitor (IDC) structures were defined on the surface of the NKN film using photolithography. The electrical characterization at 1 MHz showed dissipation factor tan delta of 0.010, tunability 16.5% at 200 kV/cm and dielectric permittivity epsilon(r)=470. The frequency dispersion of epsilon(r) between 1 kHz and 1 MHz was 8.5% and the IDCs showed very good insulating properties with leakage current density on the order of 30 nA/cm(2) at 400 kV/cm. The polarization loop exhibits weak ferroelectric hysteresis with maximum polarization 23.5 muC/cm(2) at 600 kV/cm. These results are promising for tunable microwave devices based on rf sputtered NKN thin films.

  • 17.
    Bonetti, Stefano
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Kim, Jang-Yong
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Buried tantalate-niobate microwave varactors2007In: 2006 15TH IEEE INTERNATIONAL SYMPOSIUM ON APPLICATIONS OF FERROELECTRICS, 2007, p. 347-350Conference paper (Refereed)
    Abstract [en]

    We present characteristics of microwave variable capacitors (varactors) buried in 2.5 mu m thick AgTa0.5Nb0.5O3 (ATN) film pulsed laser deposited on sapphire single crystal. 2 gm gap interdigital capacitors (IDC) were fabricated by photolithographic, dry etching and lift-off processes. For comparison, similar IDCs were also defined on top of ATN film. Capacitance and loss tangent have been determined using a modified de-embedding technique in the microwave range 25 MHz - 40 GHz. Buried structures show higher values of capacitance and tunability, keeping the same level of losses compared to standard topped devices and resulting in an increased K-factor = tunability/tan delta. Experimental results are explained within equivalent circuit model. Besides the increased performance, the new design avoids the need of a successive planarization step, which could be required in an integration process.

  • 18. Brunahl, J.
    et al.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Piezoelectric shear mode drop-on-demand inkjet actuator2002In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 101, no 3, p. 371-382Article in journal (Refereed)
    Abstract [en]

    We report on comprehensive characterization of piezoelectric shear mode inkjet actuators micromachined into bulk Pb(Zr0.53Ti0.47)O-3 (PZT) ceramics. The paper starts with an overview of different drop-on-demand inkjet systems, whereas the main attention is then turned on particular Xaar-type piezoelectric shear mode inkjet printheads. They are an example of complex microelectromechanical system (MEMS) and comprise a ferroelectric array of 128 active ink channels (75 mum wide and 360 mum deep). Detailed information about fabrication process and principles of operation are given. Since each actuating wall of 128 channels is a piezoelectric capacitor metallized from both sides to be animated by electric pulse, electrical properties of channel walls (CWs) are easy to test and serve as a fingerprint of actuator performance in the virgin state as well as after high voltage/elevated temperature heavy duties. We present several techniques to control manufacturing process and fatigue effects. So, continuous wave and pulsed spectroscopy and hysteresis P-E loop tracing showed that compared to a virgin PZT ceramics state, dielectric permittivity (epsilon') was reduced three times, the loss factor (tan delta) increased from initial 4.8 to 6.6%, remnant polarization decreased by 43%, coercive field increased by 38%, whereas Curie temperature increased from 508 to 560 K after 90,000 cycles of ferroelectric hysteresis P-E loop tracing at 50 Hz at electric field of 88.5 kV/cm. Heat treatment also results in PZT ceramics degradation: appreciable reduction of the coupling coefficient (k(15)) and the degradation of inkjet performance were revealed by optical stroboscope technique: 8.7 and 14% reduction of drop velocity and volume in electrically fatigued actuator, 2.5% reduction of drop velocity and unchanged drop volume in temperature-treated actuators.

  • 19. Brunahl, J.
    et al.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Non-destructive pulsed technique to characterize functional properties of micromachined bulk PZT2001In: Ferroelectrics (Print), ISSN 0015-0193, E-ISSN 1563-5112, Vol. 263, no 1-4, p. 1487-1492Article in journal (Refereed)
    Abstract [en]

    In this report, a non-destructive pulsed technique is presented to characterize all relevant properties of machined bulk PZT material. The proposed method is based on recording of the transient current as response on the short voltage pulse applied to the ferroelectric acoustic element. This new promising experimental technique makes it possible to measure mechanical and electrical properties fast, reliably and reproducibly. Among other results we can obtain electromechanical coupling coefficient, dielectric loss factor tan 8, mechanical quality factor Q, dielectric constant, capacitance, resonant frequency and Curie temperature T-c. The temperature dependence of above mentioned parameters can be studied as well very easily.

  • 20. Cheremisin, A. B.
    et al.
    Loginova, S. V.
    Velichko, A. A.
    Putrolaynen, V. V.
    Pergament, A. L.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Modification of Atomic Structure of Thin Amorphous V2O 5 Films under UV Laser Irradiation2008In: PROCEEDINGS OF THE 17TH INTERNATIONAL VACUUM CONGRESS/13TH INTERNATIONAL CONFERENCE ON SURFACE SCIENCE/INTERNATIONAL CONFERENCE ON NANOSCIENCE AND TECHNOLOGY, 2008Conference paper (Refereed)
    Abstract [en]

    Influence of ultra-violet radiation of the KrF laser (wave length 248 nm, pulse duration 20 ns) on atomic structure of amorphous vanadium pentoxide thin films, prepared by the pulsed laser deposition method, is studied. Calculations of the short-range order characteristics (radii and diffusiveness of coordination spheres, coordination numbers) were performed by the Finbak -Warren method. It is established that minimal structure unit of amorphous V 2O5 film before and after irradiation is a strongly deformed oxygen octahedron. Distortions of tetragonal pyramids in the initial and modified film are different. Also, oxygen deficiency in a tetragonal pyramid is observed.

  • 21. Cheremisin, Alexander
    et al.
    Putrolaynen, Vadim
    Velichko, Andrey
    Pergament, Alexander
    Kuldin, Nikolay
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    UV laser modification and selective ion-beam etching of amorphous vanadium pentoxide thin films2009Article in journal (Refereed)
    Abstract [en]

    We present the results on excimer laser modification and patterning of amorphous vanadium pentoxide films. Wet positive resist-type and Ar ion-beam negative resist-type etching techniques were employed to develop UV-modified films. V2O5 films were found to possess sufficient resistivity compared to standard electronic materials thus to be promising masks for sub-micron lithography.

  • 22. Cho, C. R.
    et al.
    Grishin, Alexander M.
    KTH, Superseded Departments, Physics.
    Background oxygen effects on pulsed laser deposited Na0.5K0.5NbO3 films: From superparaelectric state to ferroelectricity2000In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 87, no 9, p. 4439-4448Article in journal (Refereed)
    Abstract [en]

    Ambient oxygen pressure in a pulsed laser deposition process has been observed to have a critical influence on the compositional, crystalline, and electrical properties of Na0.5K0.5NbO3 (NKN) thin films grown onto polycrystalline Pt80Ir20 and SiO2 (native oxide)/Si(111) substrates. Films prepared at high oxygen pressure (similar to 400 mTorr) were found to be single phase and highly c-axis oriented. X-ray diffraction theta-2 theta scans and rocking curve data show a strong effect of NKN film self-assembling along the [001] direction regardless of the substrate texture. The high dielectric permittivity of 550, low dissipation factor of less than 3%, and high remanent polarization of 12 mu C/cm(2) indicate the high ferroelectric quality of the fabricated film. The role of the high-energy component of the erosion products has been proven to be crucial to film performance. On the other hand, films grown at low oxygen pressure (similar to 10 mTorr) have been found to be mixed phases of ferroelectric NKN and paraelectric potassium niobates. These films have shown superparaelectric behavior: 5% tunability at an electric field of 100 kV/cm, losses as low as 0.3%, and excellent stability to temperature and frequency changes.

  • 23. Cho, C. R.
    et al.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Thickness dependent performance of Na0.5K0.5NbO3/sapphire thin film varactors2001In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 39, no 1-4, p. 1353-1360Article in journal (Refereed)
    Abstract [en]

    Perfect c-axis oriented Na0.5K0.5NbO3 (NKN) films have been pulsed laser deposited on Al2O3(01 (1) under bar2) single crystals (r-cut sapphire) for voltage tunable microwave device applications. Thickness dependence of dielectric performance of the NKN/sapphire interdigital capacitors (IDCs) has been studied. 40 V bias tunability and dielectric loss tandelta of 4 burr slot IDCs have been found to be 24.6 % and 2.86 % for 1.2 mum thick NKN film, and 6.1 % and 0.83 % for 0.14 mum thick NKN film, respectively. Low leakage currents and high breakdown voltages are observed in these structures.

  • 24. Cho, C. R.
    et al.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Moon, B. M.
    Ferroelectric Na0.5K0.5NbO3 thin films by pulsed laser deposition2000In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 31, no 1-4, p. 35-45Article in journal (Refereed)
    Abstract [en]

    Highly c-axis oriented single phase Na0.5K0.5NbO3 (NKN) thin films have been deposited onto polycrystalline Pt80Ir20 substrates and SiO2/Si(001) wafers using pulsed laser ablation of stoichiometric ceramic target. Strong self-assembling of NKN films along the [001] direction has been observed. Properties of NKN/Pt thin film structures have been successfully tailored by oxygen pressure control from the ferroelectric state, characterized by the remnant polarization of 12 muC/cm(2), dielectric constant epsilon similar to 520 and tan delta - 0.024 @ 100 kHz, to superparaelectric state with tan delta as low as 0.003 and epsilon = 210 with very small 1.7% dispersion in the frequency domain 0.4-100 kHz and less than 10% Variation in the temperature range 77-415 K. NKN films grown onto SiO2/Si(001) substrates show quadrupled super-lattice structure along c-axis, loss tan delta less than 0.01, and epsilon similar to 110 @ 1 MHz. C-V measure ments for Au/NKN(270nm)/SiO2/Si MFIS-diode structure yield memory window of 3.26 V at the programmable voltage of 8 V.

  • 25. Cho, C. R.
    et al.
    Koh, J. H.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Abadei, S.
    Gevorgian, S.
    Na0.5K0.5NbO3/SiO2/Si thin film varactor2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 76, no 13, p. 1761-1763Article in journal (Refereed)
    Abstract [en]

    Perfectly c-axis oriented micrometer thick Na0.5K0.5NbO3(NKN) films have been prepared on a thermally grown ultrathin SiO2 template layer onto a Si(001) wafer by the pulsed laser deposition technique. A x-ray diffraction theta-2 theta scan reveals multiple-cell structuring of single phase NKN film along the polar axis, while films grown onto amorphous ceramic (Corning) glass show a mixture of slightly c-axis oriented NKN and pyrochlore phases. This implies a small amount of SiO2 crystallites distributed in an amorphous matrix inherit Si(001) orientation and promotes highly oriented NKN film growth. NKN film dielectric permittivity epsilon' was found to vary from 114.0 to 107.2 in the frequency range 1 kHz-1 MHz, while the resistivity was on the order of 2.6 x 10(10) Ohm cm @ 20 kV/cm. The planar interdigital variable reactance device (varactor) based on the NKN/SiO2/Si thin film structure possesses a dissipation factor of 0.8% at 1 MHz and zero bias, electrical tunability of 3.1%, and nA order leakage current at 20 V bias at room temperature.

  • 26. Cho, C. R.
    et al.
    Park, S. H.
    Moon, B. M.
    Sundqvist, J.
    Harsta, A.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Na0.5K0.5NbO3 thin films for MFIS_FET type non-volatile memory applications2002In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 49, p. 21-30Article in journal (Refereed)
    Abstract [en]

    Na0.5K0.5NbO3(NKN) thin films have been prepared on Pt80Ir20, SiO2/Si, and Ta2O5/Si substrates for ferroelectric non-volatile memory applications. Ferroelectric hysteresis loops for Au/NKN/Pt80Ir20 vertical capacitor yielded remnant polarization of 12 muC/cm(2) and coercive field similar to20 kV/cm. Significant flat-band voltage V-FB shifts with buffer layer thickness in Au/NKN/SiO2/Si structures have been attributed to the intermixing between Na and K alkali ions and SiO2 layer. On the other hand, Au/NKN/Ta2O5/Si structure exhibited wide memory window without significant V-FB deviations, low leakage currents, and rather long retention time at zero bias.

  • 27.
    Cho, Choong-Rae
    et al.
    Department of Solid State Electronics, Ångström Laboratory, Uppsala University.
    Katardjiev, Ilia
    Department of Solid State Electronics, Ångström Laboratory, Uppsala University.
    Grishin, Michael A.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Na0.5K0.5NbO3 thin films for voltage controlled acoustoelectric device applications2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 80, no 17, p. 3171-3173Article in journal (Refereed)
    Abstract [en]

    Perovskite Na0.5K0.5NbO3 (NKN) thin films have been prepared on Y+36degrees cut single crystal quartz substrates using the pulsed laser ablation technique. X-ray diffraction theta-2theta and omega-scan data demonstrate almost perfectly c-axis oriented film textures with narrow mosaic broadening. Radio frequency dielectric spectroscopy showed that the films possess relatively high dielectric permittivities, low dielectric losses, and low frequency dispersions. Capacitance-voltage (C-V) measurements for a 2 mum slot NKN/quartz interdigital capacitor yield 23.1% tunability by applying 40 V bias at 1 MHz, while C-V hysteresis indicates polarization reversal. The considerable voltage tunability with superior crystallinity in piezoelectric NKN films on quartz substrates suggests their potential use for novel voltage tunable acoustoelectric devices.

  • 28. Cortes-Perez, O.
    et al.
    Ordonez-Romero, C. L.
    Ortega-Martinez, R.
    Kolokoltsev, O. V.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Bragg difraction of optical guided waves by spin-dipole waves in double layer ferromagnetic wave guides2008In: Revista mexicana de física, ISSN 0035-001X, Vol. 54, no 5, p. 376-381Article in journal (Refereed)
    Abstract [es]

    The peculiarities of the Bragg diffraction of optical guided waves (OGWs) by spin-dipole waves (SDWs) in a new ferrite heterostructure, based on Bi3Fe5O12(BIG) thin film deposited on a standard YIG/GGG (a Yttrium Iron Garnet thin film over a Galium Gadolinum Garnet substrate) sample, is presented. It is shown that the efficiency of waveguide magnetooptic interaction between OGWs and SDWs in BIG/YIG/GGG can be 4-14 times larger than in the standard YIG/GGG waveguide, even in the case when the interacting waves are localized in YIG waveguide layer.

  • 29. Cortés-Pérez, O.
    et al.
    Ordoñez-Romero, C. L.
    Ortega-Martínez, R.
    Kolokoltsev, O. V.
    Grishin, Alexander
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Difracción de Bragg de ondas ópticas guiadas por ondas de dipolo de spin en guías de onda ferromagnéticas de doble capa2008In: Revista Mexicana de Fisica, ISSN 0035-001X, Vol. 54, no 5, p. 376-381Article in journal (Refereed)
    Abstract [en]

    The peculiarities of the Bragg diffraction of optical guided waves (OGWs) by spin-dipole waves (SDWs) in a new ferrite heterostructure, based on Bi3Fe5O12(BIG) thin film deposited on a standard YIG/GGG (a Yttrium Iron Garnet thin film over a Galium Gadolinum Garnet substrate) sample, is presented. It is shown that the efficiency of waveguide magnetooptic interaction between OGWs and SDWs in BIG/YIG/GGG can be 4-14 times larger than in the standard YIG/GGG waveguide, even in the case when the interacting waves are localized in YIG waveguide layer.

  • 30. Denysenkov, V. P.
    et al.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Broadband ferromagnetic resonance spectrometer2003In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 74, no 7, p. 3400-3405Article in journal (Refereed)
    Abstract [en]

    The continuous wave ferromagnetic resonance (FMR) spectrometer operating in multioctave (0.05-40 GHz) frequency range has been built to investigate the magnetic properties of thin ferromagnetic films in the temperature range of 4-420 K. The spectrometer has two probeheads: one is the X-band microwave reflection cavity used to perform express room temperature measurements and the other is an in-cryostat microstrip line probe to carry out FMR experiments covering the entire frequency range offered by the microwave source. Very uniform and stable magnetic field up to 2.4 T, temperature 4 K-420 K, and continuous frequency scan performed by an HP8722D vector network analyzer provide various modes of operation. Both probe heads are equipped with two-circle high precision goniometers to ensure accurate characterization of magnetic anisotropy and magnetostatic waves spectra recording. Use of the phase sensitive detection, utilized by magnetic field modulation at audio frequency and computer triggering of the network analyzer, enables broadband spectrometer sensitivity to be as high as 1.3x10(11) spins/Oe.

  • 31.
    Dzibrou, Dzmitry
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Fitting transmission and Faraday rotation spectra of Bi3Fe5O12/Sm3Ga5O12 (m) magneto-optical photonic crystals2009In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 106, no 4, p. 043901-Article in journal (Refereed)
    Abstract [en]

    A consistent microscopic approach is developed to simulate the transmittance and Faraday rotation in all-garnet heteroepitaxial magneto-optical photonic crystals (MOPCs). To compare the experimental and simulation results, [Bi3Fe5O12/Sm3Ga5O12](m) (BIG/SGG) MOPC designed to operate at a telecommunication wavelength lambda(res)=980 nm was chosen. It was composed of [BIG/SGG](5) and [SGG/BIG](5) distributed Bragg reflectors with a microcavity layer of BIG in between. The dispersion relations of the diagonal and off-diagonal elements of the permittivity tensor (epsilon) over cap for BIG in the electric dipole approximation were obtained from the simulation of the transmittance and Faraday rotation for a reference single layer BIG film. Revealed dispersion relations were then combined with the 4 x 4 matrix formalism for magnetic superlattices to compute transmission and Faraday rotation spectra of the MOPC. The results of numerical simulations were found to be in good agreement with the experimental ones.

  • 32.
    Dzibrou, Dzmitry
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Kawasaki, H.
    Pulsed Laser Deposited TiO2Films: Tailoring optical properties2008In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 516, no 23, p. 8697-8701Article in journal (Refereed)
    Abstract [en]

    TiO2 amorphous films have been pulsed laser deposited onto glass substrates. Film characterization by X-ray diffraction, atomic force microscopy and transmission spectroscopy was performed with the aim of extracting the information on the film crystalline structure, surface roughness and optical properties. Three methods for improving film optical performance have been employed, namely deposition at elevated temperatures, post-annealing in thermodynamically equilibrium conditions and rapid thermal annealing (RTA). The best characteristics were achieved in the case of the film subjected to RTA at 500 °C: refractive index n = 2.53, absorption coefficient α = 404 cm- 1 at λ = 550 nm and rms surface roughness as low as 0.6 nm. The results obtained were found to be one of the best published so far.

  • 33.
    Dzibrou, Dzmitry
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Kawasaki, Hiroharu
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Suda, Y.
    Pankov, V. V.
    Tailoring optical properties of pulsed laser deposited TiO2 films2008In: PROCEEDINGS OF THE 17TH INTERNATIONAL VACUUM CONGRESS/13TH INTERNATIONAL CONFERENCE ON SURFACE SCIENCE/INTERNATIONAL CONFERENCE ON NANOSCIENCE AND TECHNOLOGY / [ed] Johansson LSO; Andersen JN; Gothelid M; Helmersson U; Montelius L; Rubel M; Setina J; Wernersson LE, BRISTOL, ENGLAND: IOP PUBLISHING LTD , 2008, no 100, p. 082035-Conference paper (Refereed)
    Abstract [en]

    The paper is dedicated to the investigation into optical properties of TiO2 thin films pulsed laser deposited at the temperature as low as 150 degrees C and subjected to the following heat treatment. Properties of obtained nanocrystalline films were compared to polycrystalline TiO2 films grown at elevated temperatures. The highest transmission and the best morphology in polycrystalline films have been obtained at the growth temperature of 300 degrees C. The two methods of post-annealing of amorphous films were employed: annealing at thermodynamically equilibrium conditions and rapid thermal annealing (RTA). RTA at 500 degrees C enables achievement of the best optical performance: smooth surface and high films transparency.

  • 34. Emelchenko, G.
    et al.
    Steinman, E.
    Masalov, V.
    Tereshchenko, A.
    Bazhenov, A.
    Grishin, Alex M.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    1.5 μm photoluminescence of Er3+ in opal based photonic crystals2008In: Proc SPIE Int Soc Opt Eng, 2008Conference paper (Refereed)
    Abstract [en]

    The study of the emission properties of opal-erbium oxide nanocomposites in the wide range of erbium concentrations was carried out. Erbium oxide concentration was varied from 0.25 to 16%wt. Maximal output of the photoluminescence (PL) took place at 1%wt of erbium oxide concentration. It was shown that the annealing temperatures from 600 to 900°C were too low to exhibit sufficient emission properties of the erbium-opal composites. The presence of the erbium silicates Er2SiO5 and Er 2Si2O7 in the opal-erbium nanocomposites was revealed by X-ray phase analysis. Amorphous silica in opal matrix was not crystallized at the annealing during a few hours at 1000 - 1200°C. The case of the tens hours of annealing the crystoballite phase occurred. No angle dependence of the PL intensity was observed as a result of degradation of the photonic band gap (PBG) at the annealing of the opal-erbium oxide nanocomposites. Further modification of the material processing to achieve a strong photonic band gap reflection peak near 1550 nm with high PL intensity in the opal-Er2O3 composite is running.

  • 35.
    Emmoth, Birger
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Pisarev, A.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Karlsson, Ulf
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Litnovsky, A.
    Rubel, Marek J.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Wienhold, P.
    Fuel removal from bumper limiter tiles by using a pulsed excimer laser2005In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 337-39, no 1-3, p. 639-643Article in journal (Refereed)
    Abstract [en]

    Samples of a limiter tile from the TEXTOR tokamak were investigated by scanning electron microscopy and nuclear reaction analysis both before and after laser heating. SEM images showed spheres and thin flakes covering the surface which are the areas modified by plasma particles striking under grazing angles. Due to roughness of the surface there are shadowed regions between the 'flakes'. Laser pulses did not lead to expected common ablation of the surface. Features that looked like 'melting' of thin surface layers were rather observed. The initial deuterium content in the surface layer of tiles was of the order of 10(18) D atoms per cm(2). After the laser light impact the content decreased with 60-70%; by reducing the deposited power by a factor four, the deuterium content was decreased by 40-50%. We make the interpretation that we approach a threshold of the laser detritiation method in fusion devices.

  • 36.
    Fornara, Andrea
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Vogt, Carmen
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Li, Shanghua
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Qin, Jian
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Synthesis, characterization and magneto-optical properties of transparent magnetic PMMA/nanoparticles compositeManuscript (preprint) (Other academic)
  • 37. Fors, R.
    et al.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT).
    Giant resistance switching in metal-insulator-manganite junctions: Evidence for Mott transition2005In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 71, no 4Article in journal (Refereed)
    Abstract [en]

    Heteroepitaxial CeO2(80 nm)/L0.67Ca0.33MnO3(400 nm) film structures have been pulsed laser deposited on LaAlO3(001) single crystals to fabricate two terminal resistance switching devices. Ag/CeO2/L0.67Ca0.33MnO3 junctions exhibit reproducible switching between a high resistance state (HRS) with insulating properties and a semiconducting or metallic low resistance state (LRS) with resistance ratios up to 10(5). Reversible electrical switching is a polar effect achievable both in continuous sweeping mode and in the pulse regime. Successive temperature crossover of electronic transport from the thermal activation of the deep levels (E-a=320 meV) at high temperatures to thermal activation of the shallow levels (E-a=40 meV) and finally at low temperatures to the regime of temperature independent resistance, usually associated with quantum tunneling, has been found for the insulating HRS. The temperature dependence of the LRS reveals a para-to-ferromagnetic phase transition in the L0.67Ca0.33MnO3 (LCMO) electrode at T-c=260 K and an anomaly at lower temperatures similar to200 K corresponding to the Curie temperature of the Mn4+ depleted part of the LCMO film. Current-voltage characteristics in the LRS are highly nonlinear, and show negative differential conductivity (NDC). We suggest that the reversible resistance switching ocurrs due to the electric field induced nucleation of filament-type conducting valence-shifted CeOx domains inside the insulating CeO2 matrix. The abrupt insulator-to-metal transition is the result of localization of 4f electronic states in Ce3+ ions and the subsequent appearance of hole conductivity in the oxygen p-bands. NDC at low temperatures is relied upon the interband scattering of CeOx carriers from a low energy, high mobility valley into a high energy valley with low mobility.

  • 38.
    Fors, Rickard
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Khartsev, Sergiy
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Grishin, Alexander
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Non-volatile giant resistance switching in metal-insulator-manganite junctions2005In: Materials and Processes for Nonvolatile Memories / [ed] Claverie, A; Tsoukalas, D; King, TJ; Slaughter, JM, WARRENDALE: MATERIALS RESEARCH SOCIETY , 2005, Vol. 830, p. 379-384Conference paper (Refereed)
    Abstract [en]

    Heteroepitaxial CeO2(80nm)/L0.67Ca0.33MnO3(400nm) film structures have been pulsed laser deposited on LaAlO3(001) single crystals to fabricate two terminal resistance switching devices. Ag/CeO2/L0.67Ca0.33MnO3 junctions exhibit reproducible switching between a high resistance state (FIRS) with insulating properties and a semiconducting or metallic low resistance state (LRS) with resistance ratios up to 10(5). Reversible electrical switching is a polar effect achievable both in continuous sweeping mode and in the pulse regime.

  • 39.
    Fors, Rickard
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Pohl, A.
    Westin, G.
    Sol-gel derived versus pulsed laser deposited epitaxial La0.67Ca0.33MnO3 films: structure, transport and effects of post-annealing2004In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 467, no 02-jan, p. 112-116Article in journal (Refereed)
    Abstract [en]

    Epitaxial La0.67Ca0.33MnO3 films have been prepared on LaAlO3 crystals by pulsed laser deposition (PLD) and by a novel all-alkoxide sol-gel technique. Different out-of-plane lattice parameters are found for the as-prepared films, and scanning electron microscopy shows a more porous structure for sol-gel films as compared to PLD films. These differences are largely removed by post annealing at 1000 degreesC. Transport measurements show maximum temperature coefficient of resistivity of 8.2% K-1 at 258 K (PLD) and 6.1% K-1 at 241 K (sol-gel) and colossal magnetoresistance at 560 kA/m of 35% at 263 K (PLD) and 32% at 246 K (sol-gel).

  • 40.
    Fors, Rickard
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Pohl, A.
    Khartsev, Sergey
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Westin, G.
    Comparison of sol-gel derived and pulsed laser deposited epitaxial La0.67Ca0.33MnO3 films for IR bolometer2004In: Integration Of Advanced Micro-And Nanoelectronic Devices-Critical Issues And Solutions / [ed] Morais, J; Kumar, D; Houssa, M; Singh, RK; Landheer, D; Ramesh, R; Wallace, RM; Guha, S; Koinuma, H, 2004, Vol. 811, p. 379-384Conference paper (Refereed)
    Abstract [en]

    Epitaxial La0.67Ca0.33MnO3 films have been prepared on LaAlO3 crystals by pulsed laser deposition (PLD) and by a novel all-alkoxide sol-gel technique. Different out-of-plane lattice parameters are found for the as-prepared films, and scanning electron microscopy shows a more porous structure for sol-gel films as compared to PLD films. These differences are largely removed by post-annealing at 1000 degreesC. Transport measurements show maximum temperature coefficient of resistivity of 8.2 % K-1 at 258 K (PLD) and 6.1% K-1 at 241 K (sol-gel) and colossal magnetoresistance at 7 kOe of 35% at 263 K (PLD) and 32% at 246 K (sol-gel).

  • 41.
    Grishin, A. M.
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Khartsev, S. I.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Bohlmark, J.
    Ahlgren, M.
    Ultra-hard AlMgB14 Coatings Fabricated by RF Magnetron Sputtering from a Stoichiometric Target2015In: JETP Letters: Journal of Experimental And Theoretical Physics Letters, ISSN 0021-3640, E-ISSN 1090-6487, Vol. 100, no 10, p. 680-687Article in journal (Refereed)
    Abstract [en]

    For the first time hard aluminum magnesium boride films were fabricated by RF magnetron sputtering from a single stoichiometric ceramic AlMgB14 target. Optimized processing conditions (substrate temperature, target sputtering power and target-to-substrate distance) enable fabrication of stoichiometric in-depth compositionally homogeneous films with the peak values of nanohardness 88 GPa and Young's modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 and 275 GPa at 200 nm depth in 2 mu m thick film.

  • 42.
    Grishin, Alex M.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
    Multifunctional oxides on Si2005In: Proc. Electrochem. Soc., 2005, p. 482-497Conference paper (Refereed)
    Abstract [en]

    We review the projects ongoing at the Royal Institute of Technology on engineering and application of novel oxides on Si platform. Colossal magnetoresistance (CMR) in La 1-x(Sr,Ca,Pb) xMnO 3 films grown on Si has been tailored to room temperature to make a prototype of uncooled IR bolometer. Demonstrator of ferroelectric PZT/SiC field effect transistor operates at temperatures up to 300 °C. Ferroelectric niobate (Na,K)NbO 3 films have been sintered and found to be feasible for biomedical, microwave and electro-optical applications.

  • 43.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits. INMATECH Intelligent Materials Technology, Sweden; Petrozavodsk State University, Russia.
    Abrasion resistant low friction and ultra-hard magnetron sputtered AlMgB14 coatings2016In: Materials Research Express, ISSN 2053-1591, Vol. 3, no 4, article id 046402Article in journal (Refereed)
    Abstract [en]

    Hard aluminum magnesium boride films were fabricated by RF magnetron sputtering from a single stoichiometric AlMgB14 ceramic target. X-ray amorphous AlMgB14 films are very smooth. Their roughness does not exceed the roughness of Si wafer and Corning glass used as the substrates. Dispersion of refractive index and extinction coefficient were determined within 300 to 2500 nm range for the film deposited onto Corning glass. Stoichiometric in-depth compositionally homogeneous 2 μm thick films on the Si(100) wafer possess the peak values of nanohardness 88 GPa and Young’s modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 GPa and 275 GPa at 200 nm depth. Friction coefficient was found to be 0.06. The coating scratch adhesion strength of 14 N was obtained as the first chipping of the coating whereas its spallation failure happened at 21 N. These critical loads and the work of adhesion, estimated as high as 18.4 J m−2, surpass characteristics of diamond like carbon films deposited onto tungsten carbide–cobalt (WC– Co) substrates.

  • 44.
    Grishin, Alexander
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergey
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Electro-optical properties of Na0.5K0.5NbO3 films on Si by free-space coupling technique2004In: New Materials For Microphotonics / [ed] Shin, JH; Brongersma, M; Buchal, C; Priolo, F, 2004, Vol. 817, p. 225-229Conference paper (Refereed)
    Abstract [en]

    We report electro-optic performance of highly polar axis oriented Na0.5K0.5NbO3 (NKN) films grown directly on Pt(100nm)/Ti(10nm)/SiO2/Si(001) substrates by rf-magnetron sputtering. Semitransparent gold electrodes (diameter circle divide = 2 mm) were deposited ontop the NKN films by a thermal evaporation through the contact mask. Processing parameters have been specially optimized to obtain "electrosoft" NKN films with a non-linear fatigue-free P-E characteristics: low remnant P-r = 3.6 muC/cm(2) and high induced polarization P = 26 muC/cm(2) @ 522 kV/cm, and the coercive field E-c = 39 kV/cm. Electro-optical characterization of NKN/Pt/Si films has been performed using waveguide refractometry: a free-space coupling of a light beam into the thin-film waveguide modes. Intensity of TM- and TE-polarized light of 670 nm laser diode reflected from the free surface of NKN film and Au-cladding NKN/PL/Si waveguide was recorded at zero and 30 V (100 kV/cm) bias electric field. Extraordinary and ordinary refractive indices as well as electro-optic coefficient have been determined by fitting these experimental data to the Fresnel formulas. Applying 160 V (530 kV/cm) across the parallel plate NKN capacitor (circle divide = 2 mm, thickness 3 mum), modulation of the reflected light as high as 40% was achieved.

  • 45.
    Grishin, Alexander
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Khartsev, Sergey
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Dzibrou, Dzmitry
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Enhanced photoluminescence in [Er2O3/TiO2]m photonic crystals2009In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 105, no 11, p. 113122-Article in journal (Refereed)
    Abstract [en]

    We survey optical properties of [Er2O3/TiO 2]6/Er2O32/[TiO 2/Er2O3]6 photonic crystals (PCs) pulsed laser deposited on to the glass substrates. The dispersion relations of refractive indexes and extinction coefficients of the constituent materials were obtained from the comparison of experimental and simulated transmission spectra of single layer Er2O3 and TiO2 reference films. Based on these data several PCs have been designed and grown to match stop band and cavity mode resonance at wavelengths close to the 523 nm Er 3+-ion Fraunhofer 4S3/2 absorption line. Precise control of chemical composition and uniform multilayer thickness enable achievement of superior optical performance of sintered PCs. Obtained dispersion relations were combined with the 2×2 transfer matrix formalism to compute PC transmittance that appeared to be in a good agreement with the experimental spectra. Pumping PCs with 514 nm light source we observed a strong photoluminescence (PL) at 1535 nm. In PC specially designed for the resonance wavelength λres =514 nm, C-band PL intensity experiences fivefold enhancement compared to a single layer Er2 O3 film of equivalent thickness.

  • 46.
    Grishin, Alexander
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    All-garnet magneto-optical photonic crystals2008In: Journal of the Magnetics Society of Japan, ISSN 1882-2924, Vol. 32, no 2, p. 140-145Article in journal (Refereed)
    Abstract [en]

    We survey the properties of all-garnet magneto-optical (MO) heteroepitaxial film structures grown by pulsed laser deposition and rf-magnetron sputtering. 1D MO-photonic crystals (MOPCs) were composed of /4 garnet layers alternating highly gyrotropic B13Fe5O12 (BIG) and MO-passive rare earth gallium garnets. As designed, MOPCs' spectra exhibit optical stop band with the transmittance central peak caused by light localization in /2 thick BIG cavity. The first all-garnet BIG/YIG MOPC showed 140% enhancement of the Faraday rotation (FR) compared to a single layer BIG film [APL 84, 1438 (2004)]. Further improvement of MO-performance has been achieved due to the replacement of optically dense YIG by transparent Gd- (GGG), Sm- and novel La-Ga-garnets [APL 86, 141108 (2005); 87, 122504 (2005); 90, 191113 (2007); JAP 101, 053906 (2007)]. At the resonance wavelengths 750 (980) nm, specific FR F=-20.5 (-7.3) deg/m and MO-quality factor Q = 2 |F| /absorption = 66 (43.6) deg represent the highest MOPC performance achieved so far. Respectively, this is 470 (810) % and 31 (190)% enhancement compared to a single layer BIG. MO-remanence (latching capability) has been engineered in the series of BIG:GGG(n:m) superlattices. Regular alternating of lattice mismatched garnet layers impedes the nucleation of misfit dislocations, preserves a long range coherent compressive strain through the whole multilayer thickness thus results in a strong uniaxial magnetic anisotropy. 2.5 m thick BIG:GGG(3:2) film at 678 nm shows FR=1.4 deg, transmittance 82%, 92% squareness of magnetization loop, saturation and coercive fields as low as 56 and 25 Oe, respectively. Nanostructured garnets were used to build MO-visualizer and current driven MO-display [APL 88, 242504 (2006)].

  • 47.
    Grishin, Alexander
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Kim, Joo-Hyung
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergey
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Processing and on-wafer measurements of ferroelectric interdigitated tunable microwave capacitors2004In: Integration Of Advanced Micro-And Nanoelectronic Devices-Critical Issues And Solutions / [ed] Morais, J; Kumar, D; Houssa, M; Singh, RK; Landheer, D; Ramesh, R; Wallace, RM; Guha, S; Koinuma, H, 2004, Vol. 811, p. 307-312Conference paper (Refereed)
    Abstract [en]

    Na0.5K0.5NbO3 (NKN) and Pb(Zr0.53Ti0.47)O-3 (PZT) films have been grown by rf-magnetron sputtering and pulsed laser deposition techniques, correspondingly, on sapphire (Al2O3-0112, r-cut), YAlO3 + 1% Nd (Nd:YAlPO3-001), and quartz (Y+36degrees-cut) single crystal substrates. Interdigital capacitor (IDC) of coplanar waveguide (CPW) structures were defined by a standard lift off technique in a Au(0.5mum)/Cr(10nm) electrode electron beam evaporated on ferroelectric film surface. IDCs consisted of five pairs of fingers separated by 2 and 4 mum gap. On-wafer microwave characterization was performed using a workbench equipped with a coplanar probe station (Cascade Microtech) with G-S-G (Ground-Signal-Ground) Picoprobe, a network analyzer (Agilent Technologies E8364A) operating in 45 MHz to 40 GHz range and programmable power supply for de DUT (Device Under Test) biasing. Assumed equivalent circuit for the IDC/CPW structure contains planar capacitor under test C, the coplanar line with a complex impedance sigma and a parasitic capacitance C, between the signal and ground lines. The de-embedding technique has been employed to determine all six complex parameters C, sigma and C-p from S-parameter measurements performed for three different device structures: device, open and thru. NKN film interdigital capacitors on sapphire show superior performance in this microwave range: the frequency dispersion was as low as 18%, voltage tunability = 1 - C(40V)/C(0) (40 V, 200 kV/cm) about 14%, loss tangent similar to0.11, K-factor = tunability/tandelta from 131% @ 10 GHz: to 56% @ 40 GHz. The reliability of the de-embedding procedure is clearly proved by analysis of the frequency dependences of the parasitic capacitance and loss tangent as well as impedance of the coplanar line. Within the accuracy of experimental data and de-embedding calculations these values appear to be voltage independent: C-p similar to 70 fF, tan delta(p) changes from 0.07 @ 10 GHz to 0.15 @ 40 GHz; real and imaginary part of interconnect impedance increases with frequency from 0.16 Omega @ 10 GHz to 0.36 Omega @ 40 GHz and from 1.6 Omega @ 10 GHz to 5.84 Omega @ 40 GHz respectively.

  • 48.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Amplifying magneto-optical photonic crystal2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, no 6, p. 061116-Article in journal (Refereed)
    Abstract [en]

    We modeled transmission and Faraday rotation characteristics of Er-doped all-garnet [Bi3Fe5O12/Gd3Ga5O12](m) photonic crystals in view of their application in C-band magneto-optical amplifiers. It is found that 48 layered 11.4 mu m thick crystal at lambda=1532 nm provides 45 degrees Faraday rotation and transmission as high as 85% being pumped with 100 mW/980 nm solid state laser diode. (C) 2010 American Institute of Physics. [doi:10.1063/1.3479910]

  • 49.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101).
    Amplifying magneto-optical photonic crystal (vol 97, 061116, 2010)2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, no 9, article id 099901Article in journal (Refereed)
  • 50.
    Grishin, Alexander M.
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits. Petrozavodsk State University, Russian Federation .
    Jalalian, Abolfazl
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits. INMATECH Intelligent Materials Technology, Sweden.
    Tsindlekht, M. I.
    Gadolinia nanofibers as a multimodal bioimaging and potential radiation therapy agent2015In: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 5, no 5, article id 057104Article in journal (Refereed)
    Abstract [en]

    Continuous bead-free C-type cubic gadolinium oxide (Gd2O3) nanofibers 20-30 mu m long and 40-100 nm in diameter were sintered by sol-gel calcination assisted electrospinning technique. Dipole-dipole interaction of neighboring Gd3+ ions in nanofibers with large length-to-diameter aspect ratio results in some kind of superparamagnetic behavior: fibers are magnetized twice stronger than Gd2O3 powder. Being compared with commercial Gd-DTPA/Magnevist (R), Gd2O3 diethyleneglycol-coated (Gd2O3-DEG) fibers show high 1/T-1 and 1/T-2 proton relaxivities. Intense room temperature photoluminescence, high NMR relaxivity and high neutron scattering cross-section of Gd-157 nucleus promise to integrate Gd2O3 fibers for multimodal bioimaging and neutron capture therapy.

1234 1 - 50 of 184
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