Change search
Refine search result
1 - 47 of 47
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Agren, P.
    et al.
    Johansson, J.
    Andersson, K.
    Haviland, David B.
    KTH, Superseded Departments, Physics.
    Hysteretic current-voltage characteristics and Coulomb blockade in 1D-arrays of Josephson junctions2000In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 280, no 04-jan, p. 414-415Article in journal (Refereed)
    Abstract [en]

    The IV characteristics (IVC) of 1D-arrays of small capacitance Josephson junctions with E-C similar to E-J have been measured. The IVC show Coulomb blockade of Cooper pair tunneling and exhibit a pronounced hysteresis which appears to be dual to the well-known resistively shunted junction behavior of ordinary Josephson junctions. A dual serially resistive junction model is used to qualitatively explain the measured data.

  • 2. Andersson, K.
    et al.
    Delsing, P.
    Haviland, David B.
    KTH, Superseded Departments, Physics.
    Synchronous Cooper pair tunneling in a 1D-array of Josephson junctions2000In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 284, p. 1816-1817Article in journal (Refereed)
    Abstract [en]

    We have studied 1D-arrays of Josephson junctions with a gate capacitively coupled to the middle of the array. The SQUID shape of each junction enables tuning of the Josephson coupling energy, El. By adding a signal to the gate with a radio-frequency f we create a step in the I-V characteristics at the value I = 2ef: The step is clearly visible as a peak in the differential resistance dI/dV and can be seen in the whole frequency range studied (10-90 MHz).

  • 3.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    MAGNETORESISTANCE MEASUREMENTS ON SINTERED YBA2CU3O7-DELTA1990In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 165, p. 1365-1366Article in journal (Refereed)
  • 4. Axnas, J.
    et al.
    Bryntse, I.
    Safonova, I.
    Rapp, Östen.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Magnetoconductivity of polycrystalline Hg,Tl-12232000In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 284, p. 1009-1010Article in journal (Refereed)
    Abstract [en]

    The magnetoconductivity of polycrystalline Hg1-xTlxBa2Ca2Cu3O8+delta With x = 0 and 0.2 has been measured above T-c and analysed in terms of superconducting fluctuations. Such studies are numerous and successful for Y- and Bi-based materials, but still rare for Hg- and Tl-based materials. Results for the coherence lengths and the role of the Maki-Thompson contribution are briefly discussed.

  • 5. Bergsten, T.
    et al.
    Delsing, P.
    Haviland, David B.
    KTH, Superseded Departments, Physics.
    Hall resistance in two-dimensional arrays of Josephson junctions2000In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 284, p. 1818-1819Article in journal (Refereed)
    Abstract [en]

    We have measured the Hall resistance in two-dimensional arrays of ultrasmall aluminium Josephson junctions. We found that the Hall resistance was periodical with respect to an external magnetic field applied perpendicular to the plane of the array. We also found that the Hall resistance was affected by an applied voltage to a nearby gate electrode, but not by a gate plane silting underneath the array.

  • 6. Botan, V.
    et al.
    Liberman, M.
    Johansson, Börje
    Dielectric liquid phase of Bose-Einstein condensed magnetoexcitons in a double quantum well2005In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 359, p. 1439-1441Article in journal (Refereed)
  • 7. Botan, V.
    et al.
    Moskalenko, S. A.
    Johansson, Börje
    Collective elementary excitations of Bose-Einstein condensed magnetoexcitons interacting with strongly correlated electron-hole plasma2006In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 378-80, p. 1041-1042Article in journal (Refereed)
  • 8. Botan, V. V.
    et al.
    Liberman, M. A.
    Moskalenko, S. A.
    Snoke, D. W.
    Johansson, Börje
    Bose-Einstein condensation of magnetoexcitons in ideal two-dimensional system in a strong magnetic field2004In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 346, p. 460-464Article in journal (Refereed)
  • 9.
    Bruhn, Benjamin
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. University of Amsterdam, Netherlands .
    Qejvanaj, Fatjon
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Gregorkiewicz, Tom
    University of Amsterdam, Netherlands .
    Linnros, Jan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Temporal correlation of blinking events in CdSe/ZnS and Si/SiO2 nanocrystals2014In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 453, p. 63-67Article in journal (Refereed)
    Abstract [en]

    Well passivated single Si/SiO2 nanoparticles obey mono exponential blinking statistics, whereas CdSe/ZnS quantum dots follow an apparent (truncated) power-law. Log-normal distributions are found to describe the interval length histograms at least as well as power-laws, while at the same time being more physically feasible and significantly easing the determination of the exponential cutoff in the ON-time distribution. The correlation of an ON- (OFF-)interval with its temporally displaced ON (OFF) neighbors, as well as that of intermixed intervals (ON with OFF and OFF with ON neighbors) has been studied. As expected from purely random processes, the correlation coefficients for events in silicon nanocrystals equal zero, whereas positive correlations between the pure and negative correlations between the mixed states in CdSe quantum dots hint at a switching process between two distinct blinking regimes that are slower than the blinking itself.

  • 10. Durmus, Z.
    et al.
    Unal, B.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Aslan, A.
    Baykal, A.
    Synthesis and characterization of poly(1-vinyl-1,2,4-triazole) (PVTri)-barium hexaferrite nanocomposite2011In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 406, no 11, p. 2298-2302Article in journal (Refereed)
    Abstract [en]

    We present a method for the fabrication of PVTri-BaFe12O19 nanocomposites by in-situ polymerization of PVTri in the presence of synthesized BaFe12O19 nanoparticles. Nanoparticles, polymer and nanocomposite were analyzed by XRD, FTIR, TGA, TEM, NMR, GPC and conductivity techniques for structural and physicochemical characteristics. Crystallographic analysis revealed the phase as hexaferrite and X-ray line profile fitting yielded a crystallite size of 17 +/- 5 nm. Conjugation of PVTri to nanoparticle surface was assessed to be via carbonyl groups on the polymer. TG analysis revealed that 45 wt% of nanocomposite is inorganic phase (BaFe12O19). It was found out that the ac conductivity of nanocomposite under a certain frequency increases with temperature.

  • 11.
    Fabrega, Lourdes
    et al.
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Triscone, Jean-Marc
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Fivat, Patrice
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Obara, Haruhiko
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Andersson, Magnus
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Decroux, Michel
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Fischer, Oystein
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Vortex dynamics and vortex phase diagram in artificial oxide superlattices1996In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 222, no 4, p. 379-384Article in journal (Refereed)
    Abstract [en]

    DyBa2Cu3O7/(Y1-xPrx)Ba2Cu3O7 multilayers are model materials to study the nature of the vortex system in high-temperature superconductors and its dynamics. Indeed, by changing in such structures the thickness of the superconducting and the alloy layers, and the composition of the alloy, we can control at wish the critical temperature, the anisotropy and the pinning strength. Additionally, finite thickness effects may be studied. We review here our results on the study of the flux motion and phase diagram in coupled multilayers, displaying an intermediate anisotropy between those of YBa2Cu3 O-7 and Bi2Sr2CaCu2O8. Transport measurements with an applied field H/c allow to identify the solid and liquid phases in the mixed state, and reveal the presence of a field-induced crossover in the thermally activated dynamics of both phases, which lead us to draw a possible mixed state phase diagram for these artificial superconductors and correlate it to the existing results for other HTS.

  • 12. Ghiringhelli, G.
    et al.
    Brookes, N. B.
    Tjeng, L. H.
    Mizokawa, T.
    Tjernberg, Oscar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Steeneken, P. G.
    Menovsky, A. A.
    Probing the singlet character of the two-hole states in cuprate superconductors2002In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 312, p. 34-35Article in journal (Refereed)
    Abstract [en]

    Using spin-resolved resonant photoemission we have probed the singlet vs. triplet character of the two-hole state in the layered cuprates Bi2Sr2CaCu2O8+delta La2-xSrxCuO4 and Sr2CuO2Cl2. The combination of the photon circular polarization with the photoelectron spin detection gives access to the character of the photoemission final states, which correspond to the two-hole configurations localized at a (CuO4) site. In particular, the lowest energy state is found to have a very high singlet character in all the measured compounds. This can be considered as a strong indication of the existence and stability of the so-called Zhang-Rice singlets in the layered cuprates.

  • 13. Ghosh, Subhradip
    et al.
    Vitos, Levente
    Department of Physics and Astronomy, Uppsala University.
    Sanyal, Biplab
    Structural and elastic properties of Ni2+xMn1−xGa alloys2011In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 406, no 11, p. 2240-2244Article in journal (Refereed)
    Abstract [en]

    The structural parameters and the energetics of the Ni(2+x)Mn(1-x)Ga alloys have been investigated by the first-principles Exact Muffin Tin Orbital-Coherent Potential Approximation (EMTO-CPA) for 0.10 < x < 0.30. The difference in total energies (delta E) between the low-temperature tetragonal phase and the high-temperature cubic phase has been considered as a qualitative indicator of the martensitic transformation temperature T(m). The qualitative behavior of delta E with variation of x has been found to be in agreement with the experimentally observed variation of T(m) with x. The elastic constants for the entire range of x have also been calculated and the determination of a relationship between delta E and the elastic shear modulus has been attempted. It is seen that delta E varies linearly with elastic shear modulus C', qualitatively similar to the relation between T(m) and C'. The energetics calculated with the EMTO method agrees quite well with the all-electron full-potential results ensuring the accuracy of the method. These results show that the EMTO-CPA method is one of the most reliable and accurate first-principles methods, in the context of off-stoichiometric alloys which undergo martensitic phase transformations.

  • 14.
    Han, Shunhui
    et al.
    KTH, Superseded Departments, Physics.
    Andersson, Magnus
    KTH, Superseded Departments, Physics.
    Thermodynamic fluctuation in doped BiSrCaCuO superconductors with 110K phase1994In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 194-196, p. 1513-1514Article in journal (Refereed)
    Abstract [en]

    The resistivity has been carefully measured for four sintered samples of Pb and Pb/Sb doped Bi-Sr-Ca-Cu-O superconductors with the 110 K phase from zero resistance temperature up to 300 K. The thermodynamical fluctuation have been fitted on the form DELTAsigma is-proportional-to epsilon(x) (epsilon=(T-T(c))/T(c)) in the regions -4 < In epsilon < -2. By choosing T(c) in different ways, it is shown that consistent results only could be obtained when T(c) is defined according to the Lawrence-Doniach theory.

  • 15.
    Haviland, David B.
    et al.
    KTH, Superseded Departments, Physics.
    Chow, E.
    Delsing, P.
    Quantum-phase transition in 1D Josephson junction arrays2000In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 284, p. 1808-1809Article in journal (Refereed)
    Abstract [en]

    One-dimensional arrays of small capacitance SQUIDs have been studied experimentally. The effective Josephson coupling between neighboring electrodes is tunable in situ. The arrays can be tuned from a Josephson-like state, with low resistance and sharp critical current, to a Coulomb blockade state, with infinite resistance and sharp threshold voltage. A quantum phase transition occurs at the crossover between these two types of behavior, which is evident from an analysis of the temperature dependence of the zero bias resistance.

  • 16.
    Holm, William
    et al.
    KTH, Superseded Departments, Physics.
    Andersson, Magnus
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Helmersson, Ulf
    Fysik, Linköpings Universitet.
    Han, Z.
    Fysik, Linköpings Universitet.
    Study of magnetoresistance in oriented yba2cu3O7-delta thin-film1994In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 194, p. 2291-2292Article in journal (Refereed)
    Abstract [en]

    The magnetoresistance of a c-axis oriented YBa2Cu3O7-delta thin film has been measured in magnetic fields, B, up to 12 T. The magnetic field was oriented both perpendicularly and parallel to the basal plane. The temperatures ranged up to epsilon = (T-T(c))/T(c) almost-equal-to 1/3 for B parallel-to c, while for B perpendicular-to the range was limited to epsilon less-than-or-equal-to 0.16. Analysis of the data in terms of superconducting fluctuations described by the Aronov-Hikami-Larkin theory is discussed.

  • 17.
    Holm, William
    et al.
    KTH, Superseded Departments, Physics.
    Andersson, Magnus
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Ivanov, Z.G.
    Department of Physics, Chalmers University of Technology.
    Engström, U.
    Department of Physics, Chalmers University of Technology.
    Negative magnetoresistance in an yba2cu3O7-delta thin-film1994In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 194, p. 2309-2310Article in journal (Refereed)
    Abstract [en]

    Negative magnetoresistance was observed in a thin YBa2Cu3O7-delta film which could be correlated with the presence of magnetic impurities. After empirical compensation for this effect the fluctuation conductivity was well described by the Aronov-Hikami-Larkin theory.

  • 18. Hong, V. V.
    et al.
    Aune, Ragnhild E.
    KTH, Superseded Departments, Materials Science and Engineering.
    Phuc, N. X.
    Seetharaman, Seshadri
    KTH, Superseded Departments, Materials Science and Engineering.
    Nitrogenation studies of Nd2Fe17 alloys2003In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 327, no 04-feb, p. 404-409Article in journal (Refereed)
    Abstract [en]

    In the present investigation, the kinetics of nitrogenation of Nd2Fe17 alloys were studied in order to optimize the magnetic properties of the pure Nd2Fe17 alloy by the introduction of nitrogen interstitials. The nitrogenation kinetics was followed in the temperature interval 1173-1473K by the use of the thermogravimetric (TG) technique. The nitrogenated alloys were prepared from a Nd2Fe17 master alloy by heat treating in different partial pressures of nitrogen under well-controlled conditions. The results of the TG experiments showed that there was an initial incubation time before the onset of nitrogenation. The length of the incubation period was found to be a function of temperature and the partial pressure of nitrogen in the gas. The nitrogen used was of high purity (99.9999% N-2). The gas purification system adopted in the present work could effectively remove traces of reducing as well as oxidizing impurity gases in the system. In order to remove the traces of CO, CH4 and H-2, (as well as other hydrocarbons) if present, the gas was passed through a column of Cu turnings kept at 973 K. The lower portion of the Cu column was surface oxidized. The reducing gases got oxidized passing through this column and CO2 and H2O were formed. Further, the oxygen impurity in the gas (ca. 10(-2) Pa) could react with the remaining reducing gases. These products were absorbed by columns of ascarite and dehydrite, respectively. Remaining oxygen impurity in the gas could then be removed by passing the gas through a furnace containing Mg turnings at 773 K. The rate of nitrogen uptake after this period was found to increase with increasing temperature. After an initial rapid nitrogenation period, the reaction rate was found to slow down, possibly due to nitrogen atoms diffusing into the bulk. The reaction was found to be rapid, and the incubation time was conspicuously absent, when nitrogen gas was used without the purification steps mentioned earlier. Oxygen impurity in the gas was found to have a strong influence on the reaction kinetics. Heat capacity measurements, as well as magnetic hysteresis measurements, were also conducted. The heat capacity of the Nd2Fe17 master alloy, as well as that of the nitrogenated alloys, Was determined in the temperature interval 293-773 K by the use of the differential scanning calorimetric technique. From the experimental heat-capacity data the Curie temperatures of the alloys were derived. Compared to the master alloy, significantly increased Curie temperatures were obtained for the nitrogenated alloys. The magnetic measurements were conducted at 300 K by the use of a quantum design magnetometer. The results obtained indicate that the nitrogenated alloys were soft magnets as no large hysteresis loop was found to exist.

  • 19. Jaffari, G. Hassnain
    et al.
    Rehman, Atiq ur
    Iqbal, Asad M.
    Awan, M. S.
    Saleemi, Mohsin
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Extrinsic contributions to the dielectric response in sintered BaTiO3 nanostructures in paraelectric and ferroelectric regimes2017In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 525, p. 70-77Article in journal (Refereed)
    Abstract [en]

    Post sintering studies of BaTiO3 (BTO) nanoparticles are presented in detail. Bulk nanostructures were prepared via three different compaction processes, namely, uniaxial cold pressing (UCP), Cold Isostatic Pressing (CIP) and Spark Plasma Sintering (SPS). Effect of compaction technique on microstructures have been investigated and correlated with electrical response for each sample. In addition to the transport properties, temperature and frequency dependent dielectric response of variously sintered samples and bulk counterpart was recorded. Several aspects have been identified that are essential to be taken into account in order to completely understand physical processes. Drastically distinct features were observed in paraelectric (PE) regime well above ferroelectric (FE)-PE transition temperature. These features include intra grain conduction with a reduction in the magnitude of PE to FE peak dielectric constant magnitude. Role of strain, grain boundary conduction associated with observation of Maxwell Wagner relaxation and hopping conduction in dielectric and ferroelectric response have been observed and discussed. Densification with presence of oxygen vacancies, significantly enhances conductivity associated with the hopping of the carriers, in turn deteriorated ferroelectric response.

  • 20. Jena, Ambika Prasad
    et al.
    Rahaman, Moshiour
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Mookerjee, Abhijit
    Study of disorder-order transitions in Fe(x)Al(1-x) binary alloys using the augmented space recursion based orbital peeling technique2011In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 406, no 20, p. 3810-3815Article in journal (Refereed)
    Abstract [en]

    In this communication we propose a method for the study of disorder-order transitions in Fe(x)Al(1-x) binary alloys. We turn to our earlier development [1] of a combination of the recursion method introduced by Haydock et al. [2] and our augmented space approach [3] with the orbital peeling technique proposed by Burke [4] to determine the small energy differences required in obtaining the pair energies which go as input to the generalized perturbation technique [5] of studying disorder-order transitions.

  • 21. Johannson, J.
    et al.
    Schollmann, V.
    Andersson, K.
    Haviland, David B.
    KTH, Superseded Departments, Physics.
    Coulomb blockade in anodised titanium nanostructures2000In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 284, p. 1796-1797Article in journal (Refereed)
    Abstract [en]

    We investigate the electrical transport properties of narrow titanium (Ti) wires which are thinned by anodic oxidation. At temperatures below 1 K the current-voltage (IV) characteristics of the resulting Ti/TiOx nanostructures exhibit a zero current state due to the occurrence of Coulomb blockade. An indium gate electrode is placed on top of the anodised region, and the modulation of the conductance as a function of the gate voltage is investigated.

  • 22. Joyce, J. J.
    et al.
    Wills, J. M.
    Durakiewicz, T.
    Butterfield, M. T.
    Guziewicz, E.
    Moore, D. P.
    Sarrao, J. L.
    Morales, L. A.
    Arko, A. J.
    Eriksson, O.
    Delin, Anna
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Graham, K. S.
    Dual nature of the 5f electrons in plutonium materials2006In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 378-80, p. 920-924Article in journal (Refereed)
    Abstract [en]

    The electronic structure of select Pu materials is examined by means of photoemission (PES) and model calculations. We present the first photoemission results and electronic structure calculations for the material PuIn3. Results for Pu materials, including the cubic delta-phase metal and the superconductor PuCoGa5, give indication of the 5f electrons exhibiting both localized and itinerant character. These new results for PuIn3 place this compounds also in the 5f dual nature category. The dual nature of the Pu 5f electrons demarks the boundary between localized and itinerant 5f character in the actinides. The photoemission data for delta-Pu, PuIn3 and PuCoGa5 are compared against model calculations. The calculations are a mixed level model (MLM) which is a multi-electron extension of the generalized gradient approximation. Using the MLM, one obtains good agreement for the volume and total energy minimum with 4 of 5 Pu 5f electrons localized. The calculations also agree well with the PES spectra. Other computational schemes and interpretations are also reviewed.

  • 23.
    Kortegaard Nielsen, Hanne
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Martin, D. M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Leveque, Patrick
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Svensson, Bengt G.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Annealing study of a bistable defect in proton-implanted n-type 4H-SiC2003In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 340, p. 743-747Article in journal (Refereed)
    Abstract [en]

    The thermal stability and annealing kinetics of a bistable defect, recently reported by Martin (Master Thesis, KTH/ELE/FTE/2003-1) employing deep level transient spectroscopy and labelled the M-centre, has been studied using n-type epitaxially grown 4H-SiC layers implanted with 2.5 MeV protons to a dose of 1 X 10(12) cm(-2). One configuration of the bistable defect leads to two levels in the band gap, 0.42 eV (M-1) and 0.7-0.8 eV (M-3) below the conduction band edge (E-C), and another leads to one level (M-2) at E-C-0.7 eV. The defect can be switched back and forth between the two configurations by varying the applied bias and the sample temperature. Isochronal and isothermal annealing shows that the defect anneals out between 310 degrees C and 370 degrees C with a first-order kinetics process. The origin of the defect is not known but it is implantation-induced and a low-order complex.

  • 24.
    Krah, Julius H.
    et al.
    KTH, Superseded Departments, Electrical Systems.
    Bergqvist, A J
    Numerical optimization of a hysteresis model2004In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 343, no 1-4, p. 35-38Article in journal (Refereed)
    Abstract [en]

    An equation system for the anhysteretic curve and the distribution function required by a hysteresis model is suggested. A least-square fitting confirms that the solution is unique and gives optimal agreement with the measurements. Moreover, the used fitting function with three parameters replaces the measured vector, which increases simulation performance.

  • 25.
    Kumar, Mukesh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Structural, electronic and optical properties of silver delafossite oxides: A first-principles study with hybrid functional2013In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 422, p. 20-27Article in journal (Refereed)
    Abstract [en]

    Ternary delafossite compounds are potential materials for optoelectronic devices. Employing a first-principles method, we calculate the structural, electronic, and optical properties of the silver based compounds AgMO2 (M=Al, Ga or In), which crystallize in delafossite structure. Our calculations show that these AgMO2 oxides have indirect band gaps and the gap energies are in the region of 1.6-3.0 eV whereas, the lowest direct band gap energies are estimated in the range of 2.6-4.3 eV. Furthermore, we find that AgMO2 compounds exhibit a strong anisotropy for the dielectric function and absorption spectra. The absorption onset for these compounds occurs well above the band gap energies. Overall, we show that the hybrid functional improves the lattice parameters and band gap energies and the calculated values are in good agreement with the experimental values.

  • 26.
    Li, Liangxing
    et al.
    State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University.
    Li, Huixiong
    State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University.
    Hu, Jinfeng
    State Key Laboratory of Multiphase Flow, Xi’an Jiaotong University.
    Bi, Qincheng
    State Key Laboratory of Multiphase Flow, Xi’an Jiaotong University.
    Chen, Tingkuan
    State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University.
    Study on void fraction distribution in the moderator cell of Cold Neutron Source systems in China Advanced Research Reactor2007In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 393, no 1-2, p. 336-346Article in journal (Refereed)
    Abstract [en]

    A physical model is developed for analyzing and evaluating the void fraction profiles in the moderator cell of the Cold Neutron Source (CNS) of the China Advanced Research Reactor (CARR), which is now constructing in the China Institute of Atomic Energy (CIAE). The results derived from the model are compared with the related experimental data and its propriety is verified. The model is then used to explore the influence of various factors, including the diameter of boiling vapor bubbles, liquid density, liquid viscosity and the total heating power acted on the moderator cell, on the void fraction profiles in the cell. The results calculated with the present model indicate that the void fraction in the moderator cell increases linearly with heating power, and increases with the liquid viscosity, but decreases as the size of bubbles increases, and increases linearly with heating power. For the case where hydrogen is being used as a moderator, calculation results show that the void fraction in the moderator cell may be less than 30%, which is the maximum void fraction permitted from the nuclear physics point of view. The model and the calculation results will help to obtain insight of the mechanism that controls the void fraction distribution in the moderator cell, and provide theoretical supports for the moderator cell design.

  • 27.
    Li, Liangxing
    et al.
    State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University.
    Li, Huixiong
    State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University.
    Kawai, Takeshi
    State Key Laboratory of Multiphase Flow, Xi’an Jiaotong University, Xi’an.
    Chen, Tingkuan
    State Key Laboratory of Multiphase Flow, Xi’an Jiaotong University, Xi’an.
    Bi, Qincheng
    State Key Laboratory of Multiphase Flow, Xi’an Jiaotong University.
    Evaluation of the void fraction in the crescent-shape moderator cell of the CARR-CNS2008In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 403, no 12, p. 2036-2042Article in journal (Refereed)
    Abstract [en]

    The mathematical model developed in a previous paper is improved in the present paper for analyzing and evaluating the void fraction profiles in the crescent-shape moderator cell of the Cold Neutron Source (CNS) of the China Advanced Research Reactor (CARR) which is now under construction in the China Institute of Atomic Energy (CIAE). The model is then applied to the case of the CARR-CNS with liquid hydrogen as a moderator and the void fraction in the crescent-shape moderator cell of the CARR-CNS is evaluated. The calculation results show that the void fraction in the crescent-shape moderator cell less than 20%. The model and the calculation results will help to obtain insight of the mechanism that controls the void fraction distribution in the crescent-shape moderator cell, and provide theoretical supports for the moderator cell construction.

  • 28. Lundin, U.
    et al.
    Sandalov, I.
    Johansson, Börje
    Mott-Hubbard transition in the N-orbital Hubbard model2000In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 281, p. 836-837Article in journal (Refereed)
  • 29.
    Lundqvist, Björn
    et al.
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Andersson, Magnus
    KTH, Superseded Departments, Physics.
    Vortex dynamics for in- and out-of-plane magnetic fields in oxygen deficient single crystals of YBa2Cu3O7-delta2000In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 284, no Part. 1, p. 705-706Article in journal (Refereed)
    Abstract [en]

    The resistive transition into a glassy vortex state in oxygen deficient single crystals of YBa2Cu3O7-delta (YBCO) has been studied for magnetic fields 0 less than or equal to B less than or equal to 12 T along the crystallographic c-axis, parallel to the ab plane, and also with a small misalignment of 1 degrees from the ab plane. Angular sweeps of the magnetic field reveal a sharp dip in the resistivity for B \textbackslash\textbackslash ab, which is attributed to intrinsic pinning of vortices between the planes. For Bile the vortex glass line is well described by B-g(T)= B-0[(1 - T/T-c)/(T/T-c)](alpha), where B-0 is anisotropy dependent and alpha approximate to 1.0-1.2. For B \textbackslash\textbackslash ab the behaviour is significantly different, and at high magnetic fields a change to a field-independent vortex solid-to-liquid transition is observed. This behaviour disappears for small misalignments between B and ab.

  • 30.
    Marcinkevicius, Saulius
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Leon, R.
    Cechavicius, B.
    Siegert, J.
    Lobo, C.
    Magness, B.
    Taylor, W.
    Changes in carrier dynamics induced by proton irradiation in quantum dots2002In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 314, no 04-jan, p. 203-206Article in journal (Refereed)
    Abstract [en]

    The effects of proton irradiation on carrier dynamics were investigated by time-resolved photoluminescence on different InGaAs/GaAs quantum-dot (QD) structures varying in QD surface density and substrate orientation, as well as thin InGaAs quantum wells. The carrier lifetimes in the dots are much less affected by proton irradiation than in the wells. Decrease in lifetimes of only 40 percent at the highest proton dose are observed in some of the QDs, whereas an similar to20 to similar to40-fold decrease is observed in the wells. Similar trends were observed for all quantum dot samples.

  • 31. Mattesini, M.
    et al.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Sa, L.
    Hugosson, Håkan Wilhelm
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Eriksson, O.
    Electronic structure and optical properties of solid C-602009In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 404, no 12-13, p. 1776-1780Article in journal (Refereed)
    Abstract [en]

    The electronic structure and the optical properties of face-centered-cubic C-60 have been investigated by using an all-electron full-potential method. Our ab initio results show that the imaginary dielectric function for high-energy values looks very similar to that of graphite, revealing close electronic structure similarities between the two systems. We have also identified the origin of different peaks in the dielectric function of fullerene by means of the calculated electronic density of states. The computed optical spectrum compares fairly well with the available experimental data for the Vis-UV absorption spectrum of solid C-60.

  • 32.
    Mohseni, Seyed Majid
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Redjai Sani, Sohrab
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Dumas, R. K.
    Persson, J.
    Nguyen, Thi Ngooc Ahn
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Chung, Sunjae
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Pogoryelov, Ye.
    Muduli, P. K.
    Iacocca, E.
    Eklund, A.
    Åkerman, Johan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Magnetic droplet solitons in orthogonal nano-contact spin torque oscillators2014In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 435, p. 84-87Article in journal (Refereed)
    Abstract [en]

    We study microwave signal generation as a function of drive current and applied perpendicular magnetic Field in nano contact spin torque oscillators (NC-STOs) based on orthogonal (pseudo) spin valves where the Co fixed layer has strong easy plane anisotropy, and the [Co/Nil free layer has a strong perpendicular magnetic anisotropy. The orthogonal NC-STOs exhibit a dramatic transition from the conventional ferromagnetic resonance like spin wave mode to a magnetic droplet solilon mode. In particular, the field and current dependence of the droplet solilon near threshold are discussed. Near threshold the droplet solilon undergoes complex dynamics that include mode hopping, as evident in the experimental frequency domain and rnagneloresislance response.

  • 33.
    Nozaki, Hiroshi
    et al.
    Toyota Cent Res & Dev Labs Inc, Nagakute, Aichi 4801192, Japan..
    Sakurai, Hiroya
    Natl Inst Mat Sci, Namiki 1-1, Tsukuba, Ibaraki 3050044, Japan..
    Ofer, Oren
    TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3, Canada..
    Ansaldo, Eduardo J.
    TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3, Canada..
    Brewer, Jess H.
    TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3, Canada.;Univ British Columbia, Dept Phys & Astron, Vancouver, BC V6T 1Z1, Canada..
    Chow, Kim H.
    Univ Alberta, Dept Phys, Edmonton, AB T6G 2J1, Canada..
    Pomjakushin, Vladimir
    Paul Scherrer Inst, Neutron Scattering Lab, CH-5232 Villigen, Switzerland..
    Keller, Lukas
    Paul Scherrer Inst, Neutron Scattering Lab, CH-5232 Villigen, Switzerland..
    Prsa, Krunoslav
    Univ Freiburg, Phys Inst, D-79104 Freiburg, Germany..
    Miwa, Kazutoshi
    Toyota Cent Res & Dev Labs Inc, Nagakute, Aichi 4801192, Japan..
    Månsson, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Sugiyama, Jun
    Toyota Cent Res & Dev Labs Inc, Nagakute, Aichi 4801192, Japan.;Japan Atom Energy Agcy, Adv Sci Res Ctr, Tokai, Ibaraki 3191195, Japan..
    Magnetic structure for NaCr2O4 analyzed by neutron diffraction and muon spin-rotation2018In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 551, p. 137-141Article in journal (Refereed)
    Abstract [en]

    We have investigated the magnetic ground state of a novel one-dimensional compound, NaCr2O4, in which Cr2O4 double chains, i.e. zig-zag chains are aligned parallel to the b-axis, by means of both muon-spin rotation and relaxation (mu+SR) and neutron diffraction (ND) measurements. The mu+SR results reveal the formation of static antiferromagnetic order below Neel temperature (T-N = 124 K). The ND measurements also demonstrate the appearance of magnetic Bragg peaks with the propagation vector (k) over right arrow = (1, 0, 1) below T-N. Combined analyses of the mu+SR and ND data clarify that the Cr moments in each zig-zag chain are aligned ferromagnetically along the c-axis, whereas antiferromagnetically along the alpha-axis between the adjacent zig-zag chains.

  • 34. Ozkaya, T.
    et al.
    Baykal, A.
    Kavas, H.
    Koseoglu, Y.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    A novel synthetic route to Mn3O4 nanoparticles and their magnetic evaluation2008In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 403, no 19-20, p. 3760-3764Article in journal (Refereed)
    Abstract [en]

    Manganese oxide (Mn3O4) nanoparticles were successfully prepared by a novel oxidation-precipitation method based on oxidation of manganese sulfate to manganese salts and hydrolyzing with NaOH and concentrated NH3. X-ray diffraction (XRD) analysis confirmed the tetragonal haussmanite structure with average crystallite size of similar to 14 and similar to 11 nm: transmission electron microscopy (TEM) analysis showed crystallite size of 14 5 and 12 3 nm for NaOH- and NH3-hydrolyzed samples, respectively. The ferromagnetic transition temperatures are 38 and 40 K for NaOH- and NH3-hydrolyzed samples, respectively. These values are lower than that of bulk Mn3O4. Both samples show superparamagnetic behavior at room temperature, with no apparent saturation magnetization and hysteresis in the region of measured field strength, and they also exhibit relatively large coercivity below the ferromagnetic transition temperature. Below the transition, marked differences are observed in temperature dependence of magnetization, hysteresis loop shape, and type of the samples from the bulk values. The particles are considered as single magnetic domains with random orientations of magnetic moments and thermal fluctuations of anisotropic axes. These results are attributed to the smaller size (increase in surface to volume ratio) of the samples, which cause an increase of effective magnetic surface anisotropy.

  • 35.
    Qiu, Min
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    He, Sailing
    KTH, Superseded Departments, Electromagnetic Theory.
    Interference of signals in parallel waveguides in a two-dimensional photonic crystal2001In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 299, no 02-jan, p. 187-193Article in journal (Refereed)
    Abstract [en]

    The interference of signals in parallel waveguides in a two-dimensional photonic crystal is studied and compared for two different types of waveguides, namely, an air waveguide formed by removing a row of dielectric columns, and a dielectric waveguide formed by introducing a dielectric slab inside the photonic crystal. For the case of air waveguides, two such parallel waveguides should be separated by at least five rows of dielectric columns to avoid interference between signals (with frequencies in the band gap) traveling in different waveguides. For the case of dielectric slab waveguides, one can achieve very low energy leakage (with negligible interference) between two such waveguides even if they are separated by only a single row of dielectric columns. A dielectric slab waveguide in a photonic crystal is more efficient for confining the electromagnetic energy inside the waveguide than an air waveguide in the photonic crystal.

  • 36. Rahaman, Moshiour
    et al.
    Tarafder, Kartick
    Sanyal, Biplab
    Mookerjee, Abhijit
    Study of optical response in disordered alloys using the generalized recursion in augmented space: Application to ferromagnetic FeCo alloy2011In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 406, no 11, p. 2121-2125Article in journal (Refereed)
    Abstract [en]

    We propose and briefly describe the generalized recursion in augmented space using a minimal TB-LMTO basis set for the calculation of configuration averaged current response functions in disordered binary alloys. Since disorder in the current terms is off-diagonal and non-separable, single-site mean-field approaches are unable to deal with it without further approximations. The augmented space approach is ideally suited for such situations and the generalized recursion proposed by Viswanath and Muller provides a fast and accurate O(N) technique for the actual calculations of the configuration averaged susceptibilities. We have applied the method to the disordered FeCo alloy. The results agree reasonably well with available experimental data on ordered versions of both the alloy systems, with extra broadening due to disorder induced lifetime effects.

  • 37. Rummukainen, M
    et al.
    Slotte, J
    Saarinen, K
    Radamson, Henry H.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Hallstedt, Julius
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Kuznetsov, A Y
    Vacancy-impurity pairs in n-type Si1-xGex studied by positron spectroscopy2006In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 376, p. 208-211Article in journal (Refereed)
    Abstract [en]

    Positron annihilation spectroscopy was applied to study relaxed P-doped n-type Si1-xGex layers with Ge concentrations up to 30%. As-grown SiGe layers were defect-free and annihilations are superpositions from bulk Si and Ge. Proton irradiation at 2 MeV energy with a 1.6 x 10(15) cm(-2) fluence was used to produce saturated positron trapping in monovacancy related defects. The defects were identified as V-P pairs, the E-center. The distribution of Si and Ge atoms surrounding the E-center is the same as in the host lattice. The vacancy migration process leading to the formation of V-P pairs therefore does not seem to have a preference for either Si or Ge atoms. (c) 2005 Elsevier B.V. All rights reserved.

  • 38.
    Rydh, Andreas
    et al.
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Andersson, Magnus
    KTH, Superseded Departments, Physics.
    Magnetic field scaling of the vortex glass resistivity in oxygen deficient YBa2Cu3O7-delta single crystals2000In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 284, p. 707-708Article in journal (Refereed)
    Abstract [en]

    The in-plane resistivity of an oxygen deficient YBa2Cu3O7-delta single crystal has been measured as a function of magnetic field B \\ c-axis in the range 0 T less than or equal to B less than or equal to 12 T. A scaling relation is found for the linear resistivity at p less than or similar to 0.1 rho(n) above the glass line that incorporates all studied temperatures and magnetic fields. Our scaling can be understood within a simple model where the mean pinning energy balances the thermal energy at the glass transition, U-0(B, T-g) = k(B)Th(g), with U-0(B, T) resembling a generalized condensation energy, U-0 similar to (1 - T/T-c)(m)/B-beta.

  • 39. Sato, K.
    et al.
    Fukushima, T.
    Toyoda, M.
    Kizaki, H.
    Dinh, V. A.
    Fujii, H.
    Bergqvist, Lars
    Department of Physics and Materials Science, Uppsala University.
    Dederichs, Peter H.
    Katayama-Yoshida, H.
    First-principles material design and perspective on semiconductor spintronics materials2009In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 404, no 23-24, p. 5237-5243Article in journal (Refereed)
    Abstract [en]

    We investigate the electronic structure and magnetic properties of III–V compound semiconductor based dilute magnetic semiconductors (DMS) from first-principles. The electronic structure of DMS is calculated by using the Korringa–Kohn–Rostoker coherent potential approximation (KKR-CPA) method in connection with the local density approximation (LDA). Describing the magnetic properties by a classical Heisenberg model, effective exchange interactions are calculated by applying magnetic force theorem for two impurities embedded in the CPA medium. With the calculated exchange interactions, TC is estimated by using the mean field approximation, the random phase approximation and the Monte Carlo simulation. In the above compounds, the magnetic interactions are well described from double exchange picture. Due to the short-range interactions, high-TC is difficult to achieve in the presently investigated materials. Based on the present results, two strategies towards high-TC are proposed to realize useful DMS materials. One uses spinodal decomposition to realize high blocking temperature in super-paramagnetic blocking phenomena and the other uses co-doping method to realize high concentration doping of magnetic impurities for high-TC.

  • 40. Shu, J.
    et al.
    Zhang, X.
    Wang, P.
    Chen, R.
    Zhang, H.
    Li, D.
    Zhang, Pei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics. National Laboratory of Solid State Microstructures, Department of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China.
    Xu, J.
    Monte-Carlo simulations of optical efficiency in luminescent solar concentrators based on all-inorganic perovskite quantum dots2018In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 548, p. 53-57Article in journal (Refereed)
    Abstract [en]

    Luminescent solar concentrator (LSC) devices emerge as a promising technology to reduce the cost of electricity generated by photovoltaic solar cells. Here, we demonstrate the detailed fabrication process of non-crystalline LSC prototype devices based on all-inorganic perovskite quantum dots (QDs) for the first time. The as-prepared all-inorganic perovskite QDs show many advantages, such as tunable absorption spectrum over the entire visible spectral region, high photoluminescence (PL) quantum yield (QY) up to 50%, and narrow emission line widths with FWHM (full width at half maximum) of 17–26 nm, which may greatly improve the optical efficiency of LSC prototype devices. On the optimal doping concentrations, Monte Carlo ray-tracing simulations indicate the LSC prototype devices have an extremely high average optical efficiency, which is 1.22% for CsPbCl3 QDs, 5.43% for CsPbBr3 QDs, and 7.39% for CsPbI3 QDs, respectively. We anticipate these potential high-efficiency LSC prototype devices based on perovskite QDs will shed light on future research of large-scale and high-performance LSCs applications.

  • 41. Slotte, J.
    et al.
    Saarinen, K.
    Kuznetsov, A. Y.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Vacancy type defects in Al implanted 4H-SiC studied by positron annihilation spectroscopy2001In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 308, p. 664-667Article in journal (Refereed)
    Abstract [en]

    Vacancy-type defects produced by 100 keV Al+ ion implantation in epitaxial 4H-SiC have been studied by positron annihilation spectroscopy. The implantation dose varied from 3 x 10(13) to 1 X 10(15)/cm(2) and the implantation temperature was 25-800degreesC. From the experimental results it is clear that the implantation at elevated temperatures reduces the number of vacancy type defects. Furthermore, the defect-cluster size depends on the implantation temperature, suggesting that the vacancies involved are mobile. The positron annihilation experiments also suggest that the defect profile extends deeper into the samples than expected from the deposited energy distribution and from previous Rutherford backscattering/channeling measurements.

  • 42. Stoltz, D.
    et al.
    Bielmann, M.
    Schlapbach, L.
    Bovet, M.
    Berger, H.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Stoltz, S. E.
    Starnberg, H. I.
    Atomic origin of the scanning tunneling microscopy images of charge-density-waves on 1T-TaSe22008In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 403, no 13-16, p. 2207-2210Article in journal (Refereed)
    Abstract [en]

    We show atomically resolved scanning tunneling microscopy (STM) images of charge density waves (CDWs) at room temperature together with angle-resolved photoelectron band-mapping of 1T-TaSe2. By comparing the results of these two techniques, we demonstrate the atomic structure of the CDW-features observed by the STM and atomic origin of the reconstructed band-structure in this material.

  • 43.
    Stoltz, Dunja
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Stoltz, S. E.
    X-ray photoelectron diffraction investigation of the cleavage plane in IT-transition metal dichalcogenides2007In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 398, no 1, p. 172-177Article in journal (Refereed)
    Abstract [en]

    We present a detailed study of the three members of the 1 T-transition metal dichalcogenides: TiSe2, TaSe2 and TaS2 by means of the X-ray photoelectron diffraction combined with single-scattering simulations. Our simulations of different surface terminations and their comparison with the measured diffraction patterns allow to determine that the cleavage occurs within the van der Waals gap. Singlescattering calculations are shown to simulate very well the measured diffractograms on these compounds.

  • 44.
    Stoltz, Dunja
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Stoltz, S. E.
    Widstrand, S. M.
    Johansson, L. S. O.
    Investigation of surface structure related features in the multiple-scattering simulations of photoelectron diffraction of 3C-SiC(001)-c(4 x 2)2007In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 395, no 1-2, p. 130-137Article in journal (Refereed)
    Abstract [en]

    In this paper we have conducted a systematic study of the photoelectron diffraction (PED) effects from the 3C-SiC(0 0 1)-c(4 x 2) surface by means of multiple-scattering calculations. Two models have been proposed to describe this surface: alternately up and down dimers (AUDD) [P. Soukiassian, F. Semond, L. Douillard, A. Mayne, G. Djuradin, L. Pizzagalli, C. Joachim, Phys. Rev. Lett. 78 (1997) 9071, based on the scanning tunneling microscopy data, and missing-row asymmetric-dimer (MRAD) [W. Lit, P. Kruger, J. Pollmann, Phys. Rev. Lett. 81 (1998) 2292], based on the total energy pseudopotential calculations. By calculating PED patterns from different emitters in these two models, we show that the surface structure induced features are visible even in total emission diffraction patterns. For the overall diffractogram a scatterer properties of the first layer under the surface become crucial due to the backscattering at low kinetic energies. This layer is Si-layer in the MRAD model, but C-layer in the AUDD model. While this causes clear differences between the diffraction patterns of the AUDD and the MRAD models, it is shown to diminish the differences between the PED patterns of the AUDD and the other models which consist of only one monolayer of Si on top.

  • 45.
    Tjernberg, Oscar
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Finazzi, M.
    Duo, L.
    Ghiringhelli, G.
    Ohresser, P.
    Brookes, N. B.
    Resonant spin resolved photoemission on Ce2000In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 281, p. 723-724Article in journal (Refereed)
    Abstract [en]

    Spin resolved resonant photoemission using circularly polarized light has been performed on thick gamma-Ce films and the measured photoelectrons show a high degree of polarization in agreement with a simple model calculation. The two near Fermi edge features are shown to influence the polarization spectrum in opposite directions, as intuitively expected for states with opposite spin-orbit alignment.

  • 46. Wong-Leung, J.
    et al.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Svensson, B. G.
    A comparison of extended defect formation induced by ion implantation in (0001) and (11(2)over-bar-0) 4H-SiC2003In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 340, p. 132-136Article in journal (Refereed)
    Abstract [en]

    We study the effect of substrate orientation on defect formation in 4H-SiC. Both (1 1 (2) over bar 0) and (0 0 0 1) n-type 4H-SiC substrates were implanted with 400 keV P. The various samples, both as-implanted samples and annealed, were studied by Rutherford backscattering and channeling and transmission electron microscopy in an attempt to understand the damage evolution and defect structures resulting from different crystal orientations. Secondary ion mass spectrometry (SIMS) was performed for P elemental profiling before and after annealing. We observe a significantly different damage accumulation in the two directions with a broader amorphous layer formed in the c-cut crystal compared to the a-cut crystal. The annealing of the damage results in a range of different defects including dislocation loops and voids in both a-cut and c-cut crystals. The SIMS profiles show in some cases distinct differences between the two crystal directions.

  • 47. Xiao, S. S.
    et al.
    He, Sailing
    KTH, Superseded Departments, Electromagnetic Theory.
    FDTD method for computing the off-plane band structure in a two-dimensional photonic crystal consisting of nearly free-electron metals2002In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 324, no 01-4, p. 403-408Article in journal (Refereed)
1 - 47 of 47
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf