Change search
Refine search result
12 1 - 50 of 89
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • 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.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    A possible way to use student peer review to improve report writing skills2012Conference paper (Other academic)
  • 2.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Comment on “Superconducting state of Ca-VII below a critical temperature of 29 K at a pressure of 216 GPa”2011In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, no 21Article in journal (Refereed)
    Abstract [en]

    In a recent paper, Sakata et al. [ Phys. Rev. B 83 220512 (2011)] report on superconductivity at 29 K in Ca under high pressure. Here, I argue that their method to define the onset of the superconducting transition temperature from resistivity measurements is misleading and that the correct value for the onset of the transition based on resistivity data shown in their paper should be 21 K. The discrepancy between these two temperatures is explained by superconducting fluctuations occurring at temperatures above the superconducting transition temperature.

  • 3.
    Andersson, Magnus
    KTH, Superseded Departments, Physics.
    Development of a rotation sample holder with high angular resolution1999Report (Other academic)
  • 4.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Helt orimliga förhoppningar2012In: Forskning och framsteg, ISSN 0015-7937, no 2, p. 72-72Article in journal (Other (popular science, discussion, etc.))
  • 5.
    Andersson, Magnus
    KTH, Superseded Departments, Physics.
    Studies of magnetoresistance and Y substitutions in YBa2Cu3O7-delta high temperature superconductors1992Doctoral thesis, comprehensive summary (Other academic)
  • 6.
    Andersson, Magnus
    KTH, Superseded Departments, Physics.
    The Oxford cryostat - a manual1991Report (Other academic)
  • 7.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Towards an engineering approach to quality in engineering education2015In: Proceedings of 5:e Utvecklingskonferensen för Sveriges ingenjörsutbildningar, 2015, p. 13-14Conference paper (Other academic)
    Abstract [en]

    Education quality is handled at many different levels in an education system, ranging all the way from external reviews of education programs at the top university level to the creation of effective learning conditions for students at the practitioners level. Each level has its own processes for quality assurance, and those processes are usually quite different. Here, I suggest one way of joining the different quality processes into a coherent model, which at the same time retain the main conceptual ideas of the already existing quality processes. The proposed model is presented as a flow diagram of an education system together with an idea about how to create both a trouble- shooting and a quality enhancement scheme based on this model. The model is inspired by the way engineers look at quality assurance in engineering systems and it can, hence, be particularly interesting for engineering educations. 

  • 8.
    Andersson, Magnus
    KTH, Superseded Departments, Physics.
    User manual for the 4He cryostat with an 8 T superconducting coil1998Report (Other academic)
  • 9.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Börjesson, Lars
    Physics Department, Chalmers University of Technology.
    Jarlborg, T
    Departement de Physique de la Matière Condensée, Université de Genève.
    Phuong, HV
    Physics Department, Chalmers University of Technology.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    RELATION BETWEEN THE CU(1)-O(4) DISTANCE AND T(C) IN Y1-2XCAXTHXBA2CU3O7-DELTA - RAMAN-SCATTERING AND CALCULATION OF THE ELECTRON-PHONON INTERACTION1992In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 46, no 10, p. 6501-6504Article in journal (Refereed)
    Abstract [en]

    The strong depression of T(c) with Ca-Th substitution in Y1-2xCaxThxBa2Cu3O7-delta has been investigated in a model calculation of the electronic and phononic contributions from the apex oxygen, O(4), on the electron-phonon interaction, lambda. The shift with Ca-Th substitution of the characteristic O(4) vibrational mode was measured by Raman scattering. The electronic part eta of lambda has been calculated at several distances between chain Cu(1) and O(4) in the region of the observed variation with x. Eta was found to depend strongly on this distance. The results show a small increase with x of the O(4) frequency and a strong decrease of eta. Both these factors thus contribute to a decrease of lambda. We therefore find evidence that a decreasing electron-phonon interaction is associated with the depression of T(c) in Ca-Th substituted YBa2Cu3O7-delta.

  • 10.
    Andersson, Magnus
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    de Boissieu, M.
    Bruehne, S.
    Drescher, C.
    Assmus, W.
    Ohahshi, S.
    Tsai, A. P.
    Mihalkovic, M.
    Krajci, M.
    Rapp, Östen
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Electronic and structural properties of Laves-phase MgZn(2) of varying chemical disorder2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, no 2, p. 024202-Article in journal (Refereed)
    Abstract [en]

    The C14 Laves-phase MgZn(2) has been investigated from 30 to 36 at. % Mg. In this way chemical disorder can be monitored over a limited concentration range and the influence on electron properties can be investigated. Our studies include thermodynamic calculations of atomic configurations of Mg and Zn at off-stoichiometric compositions, electronic-transport measurements, and electronic band-structure calculations of MgZn(2). The disorder introduced by alloying was found to be substitutional for all C14 alloys, and to have a markedly stronger effect on resistivity and magnetoresistance, Delta rho(B)/rho(0), on the Mg-rich side due to strain introduced when Mg substitutes for Zn. rho(T) and Hall constant were characteristic for weakly disordered binary alloys. Delta rho/rho of MgZn(2) was large, reached 6 at 4.2 K and 8 T, and decreased strongly at off-stoichiometric compositions. The results are discussed in view of the band-structure results and in terms of relations between atomic order and electronic properties. Several properties were found to resemble pure Zn. An empirical correlation over more than six orders of magnitude in Delta rho/rho was found for Zn and Zn-based alloys.

  • 11.
    Andersson, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Material- och nanofysik.
    Delin, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Material- och nanofysik.
    A quality process for assessing mathematics in a study programme2018In: Proceedings från 6:e utvecklingskonferensen för Sveriges ingenjörsutbildningar / [ed] Lena Petersson, Kristina Edström, Oskar Gedda, Fredrik Georgsson, Liselott Lycke och Marie Arehag, 2018Conference paper (Refereed)
    Abstract [en]

    We present two methodologies to assess the use of mathematics in a study programme. Firstly, we use a relatively simple methodology to assess how students show their ability to use mathematics in their degree project reports. Secondly, we present a methodology to assess how mathematics is used during a study programme. We have applied the first methodology on the mathematics content in 114 randomly chosen bachelor degree reports from 6 different study programmes within the fields of electrical engineering and computer engineering at KTH. For the 3-year bachelor degree programmes in computer engineering, we find clear deficits in the way students use mathematics in their bachelor degree reports as compared to the other programmes in our study. Through the second methodology, we were able to relate the deficits in the bachelor degree reports to a programme structure where skills in mathematics have not been sufficiently demanded in the engineering courses of the programme. 

  • 12.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Eltsev, Yuri
    KTH, Superseded Departments, Physics.
    Lundqvist, Björn
    KTH, Superseded Departments, Physics.
    Rydh, Andreas
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Vortex liquid properties in optimally doped and oxygen-deficient YBa2Cu3O7-delta single crystals2000In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 332, no 1-4, p. 86-92Article in journal (Refereed)
    Abstract [en]

    The electrical anisotropy, gamma = (m(c)/m(ab))(1/2), can easily be varied by changing the oxygen content in single crystals of YBa2Cu3O7-delta (YBCO); thus making this system useful as a test system For vortex dynamics in high-temperature superconductors (HTSC). Here, some recent results are reviewed. Measurements of the c-axis resistivity with the magnetic field B II ab-plane is shown to be a powerful tool in studying vortex velocity correlations both parallel and perpendicular to the applied field. In optimally doped crystals, we iind evidence that the in-plane vortex lattice melts at T-m into a disentangled vortex liquid, which looses its correlation along the c-axis at a higher temperature T-br > T-m. For weakly disordered crystals and magnetic fields B \\ c-axis, a relation between the vortex glass line and the magnetic field dependence of the characteristic energy, U*, in the pinned vortex liquid is proposed. This approach is shown to give support to our idea of describing the vortex glass resistivity in the liquid regime by a modified glass correlation Length, xi(g) = xi(0)\k(B)T/U-0 - 1\(-nu) which depends on the average pinning energy, Lr,, in the system [A. Rydh, O. Rapp, M. Andersson, Phys. Rev. Lett. 83 (1999) 1850].

  • 13.
    Andersson, Magnus
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Espinosa-Arronte, Beatriz
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    van der Beek, C. J.
    Nikolaou, M.
    Lidmar, J.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Wallin, M.
    A vortex solid-to-liquid transition with fully anisotropic scaling2009In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 150, no 5Article in journal (Refereed)
    Abstract [en]

    The vortex solid-to-liquid transition has been studied in heavy ion irradiated untwinned single crystals of YBa2Cu3O7-delta with an inclined applied magnetic field. For magnetic fields tilted at angles about 45 degrees away from the columnar defects, we find that the electric resistivity in the vortex liquid regime approaches zero with power laws in the reduced temperature T - T-c that have different exponents in all three spatial directions. Since the symmetry in the problem has been broken in two non-collinear directions by i) the direction of the columnar defects and ii) the direction of the applied magnetic field, our findings give evidence for a new type of critical behavior with fully anisotropic critical exponents. A possible view of the vortex topology for the transition is also suggested.

  • 14.
    Andersson, Magnus
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Feuerbacher, M.
    Rapp, Östen
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Magnetoresistance and Hall effect of the complex metal alloy Mg2Al32008In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 78, no 2Article in journal (Refereed)
    Abstract [en]

    Unusual electronic transport properties have been found in the rhombohedral beta'-phase of the complex metallic alloy Mg2Al3. The magnetoresistance (MR) is 2 orders of magnitude larger than in the related cubic beta-Mg2Al3-phase and Kohler's rule is strongly violated in the beta'-phase at higher temperatures. Above about 100 K the Hall coefficient R-H of the beta- and beta'-phases are similar and free-electron-like, while in the beta'-phase, R-H changes sign with decreasing temperature at low fields. We have inquired into the sources of these transport anomalies, but have not been able to clearly identify the grounds. Several conventional mechanisms for a large magnetoresistance are discussed, and found not to be applicable. The different properties in the beta- and the beta'-phases are puzzling since the magnitudes of the electrical resistivities are similar and omega(c)tau (cyclotron frequencyxscattering time) is equally small in both phases. The similar temperature range in which anomalies occur in the beta'-phase in the resistivity, the Hall effect, and the magnetoresistance indicates an electronic transition or a change of the electron structure in this phase below about 100 K.

  • 15.
    Andersson, Magnus
    et al.
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Fivat, Patrice
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Fabrega, Lourdes
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Obara, Haruhiko
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Decroux, Michel
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Triscone, Jean-Marc
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Fischer, Oystein
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Vortex solid-to-liquid transition in DyBa2Cu3O7-delta/(Y0.45Pr0.55)Ba2Cu3O7-delta multilayers1996In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 54, no 1, p. 675-681Article in journal (Refereed)
    Abstract [en]

    Current-voltage (I-V) characteristics of a coupled multilayer system consisting of thin (24 Angstrom) superconducting layers of DyBa2Cu3O7-delta each separated by 96 Angstrom of (Y0.45Pr0.55)Ba2Cu3O7-delta have been studied in the mixed state. Analyses of vortex glass scaling and signs of the clean system melting transition in the dynamics of our multilayers both suggest that the vortex system is close to three-dimensional for magnetic fields up to several T. Therefore, the theoretically predicted crossover when in-plane vortex correlations become more important than out-of-plane vortex correlations (occurring at a few tenths of a T in our multilayers) does not correspond to a complete decoupling of the superconducting layers in these materials.

  • 16.
    Andersson, Magnus
    et al.
    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.
    Fabrega, Lourdes
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Triscone, Jean-Marc
    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.
    H-T PHASE-DIAGRAM OF DYBA2CU3O7-DELTA(Y0.45PR0.55)BA2CU3O7-DELTA MULTILAYERS IN THE MIXED-STATE1994In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 235, p. 2617-2618Article in journal (Refereed)
    Abstract [en]

    From measurements of I-V characteristics of DyBa2Cu3O7-delta/(Y0.45Pr0.55)Ba2Cu3O7.delta multilayers, we have experimentally determined the characteristic temperature separating the vortex liquid from the vortex solid. We suggest that the cross-over temperature is determined by the anisotropy given by the artificially layered structure of these multilayers and that the studied system can be used as a test system for vortex dynamics.

  • 17.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Hegedüs, Zsolt
    Arrheniulaboratoriet, Stockholms Universitet.
    Hörlin, Tom
    Arrheniuslaboratoriet, Stockholms Universitet.
    Nygren, Mats
    Arrhemiuslaboratoriet, Stockholms Universitet.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Wen, T. L.
    Arrheniuslaboratoriet, Stockholms Universitet.
    (Ca,Pr) substitutions in Y- and Sm-based 1:2:3 superconductors1992In: / [ed] Per-Anker Lindgård, Odense, Denmark: Risø National Laboratory , 1992, p. 236-236Conference paper (Other academic)
  • 18.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Hegedüs, Zsolt
    Arrheniuslaboratoriet, Stockholms Universitet.
    Nygren, Mats
    Arrheniuslaboratoriet, Stockholms Universitet.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    STRUCTURAL, THERMAL AND ELECTRICAL STUDIES OF THE Y1-2XCAXTHXBA2CU3O7-DELTA SYSTEM WITH 0 LESS-THAN-OR-EQUAL-TO 0.201989In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 160, no 1, p. 65-68Article in journal (Refereed)
  • 19.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Lundqvist, Björn
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Rapp, Östen
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Vortex liquid-to-solid transition in underdoped YBa2Cu3O7-delta single crystals with B parallel to ab2003In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 388, p. 691-692Article in journal (Refereed)
    Abstract [en]

    A nearly magnetic field independent vortex liquid-to-solid transition has been observed in both the ab-plane and in the c-axis resistivity of underdoped YBa2Cu3O7-delta single crystals for magnetic fields Bparallel toab-plane. These observations suggest that intrinsic pinning caused by the superconducting layers do neither lead to a system of completely decoupled superconducting layers nor to a smectic vortex phase at high fields. A possible explanation may include a transition driven by changes in elastic properties (e.g., the shear modulus) of the vortex system.

  • 20.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    MAGNETORESISTANCE MEASUREMENTS ON (CA,TH)-DOPED YBA2CU3O7-DELTA1991In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 185, p. 1901-1902Article in journal (Refereed)
    Abstract [en]

    Magnetoresistance measurements on sintered Y1-2xCaxThxBa2Cu3O7-delta samples with x < = 0.1 are reported. By fitting the measured data to the Hikami-Larkin theory, we obtain coherence lengths, xi-ab and xi-c’ and a phase breaking time tau-phi All these parameters are found to decrease with (Ca,Th) doping. We also conclude that magnetoresistance measurements are highly sensitive to inhomogeneities in the sample.

  • 21.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    MAGNETORESISTANCE MEASUREMENTS ON POLYCRYSTALLINE YBA2CU3O7-DELTA1991In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 44, no 14, p. 7722-7725Article in journal (Refereed)
    Abstract [en]

    The magnetoresistance of a polycrystalline sample of YBa2Cu3O7-delta has been measured by an ordinary resistive method at temperatures from about 1 to 15 K above T(c) and in magnetic fields up to 12 T. From our experimental results and the theory of Hikami and Larkin, we obtain values of the coherence lengths xi-ab = 15.6 angstrom and xi-c = 3.6 angstrom and of the phase-breaking time tau-phi = 1.8 x 10(-13) s.

  • 22.
    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)
  • 23.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    UPPER CRITICAL MAGNETIC-FIELD OF Y1-2XCAXTHXBA2CU3O7-DELTA1989In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 162, p. 725-726Article in journal (Refereed)
  • 24.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Hegedüs, Zsolt
    Arrheniuslaboratoriet, Stockholms Universitet.
    Wen, TL
    Arrheniuslaboratoriet, Stockholms Universitet.
    Nygren, Mats
    Arrheniuslaboratoriet, Stockholms Universitet.
    STRUCTURAL AND SUPERCONDUCTING PROPERTIES OF Y1-2XCAXPRXBA2CU3O7-GAMMA1992In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 190, no 3, p. 255-260Article in journal (Refereed)
    Abstract [en]

    Samples of the nominal composition Y1-2xCaxPrxBa2Cu3O7-delta with 0 less-than-or-equal-to x less-than-or-equal-to 0.4 have been studied by X-ray diffraction techniques, chemical analyses, and measurements of the super conducting transition temperature and the upper critical magnetic field. For x less-than-or-equal-to 0.25, the results indicate that Ca and Pr can both replace Y in agreement with the nominal composition, while for x > 0.25 only Pr enters the orthorhombic unit cell. Compared to Pr substitution in 1:2:3 we observe small changes in the depression of T(c) and strong changes in the critical field slopes. These results suggest that if Pr has a magnetic pair-breaking effect, it is close to being temperature independent.

  • 25.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments (pre-2005), Physics.
    Rapp, Östen
    KTH, Superseded Departments (pre-2005), Physics.
    Tellgren, Roland
    Institutet för kemi, Uppsala Universitet.
    Neutron-diffraction studies of Ca-Pr doped YBa2Cu307-delta1993In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 205, no 1-2, p. 105-110Article in journal (Refereed)
    Abstract [en]

    We have performed neutron powder diffraction on samples in a series Y1-2xCaxPrxBa2Cu3O7-delta, with x=0.0, 0.1 and 0.2, and analyzed the data with the Rietveld refinement method. Small changes were observed in atomic bond distances when the amount of Ca-Pr was increased. In general, these changes could qualitatively be viewed as the sum of effects from the Ca and Pr substitutions in YBa2Cu3O7-delta samples. Analyses of the distance between the superconducting CuO2 Planes suggest that the Pr ions in the Ca-Pr substituted samples have an effective valence close to + 4.

  • 26.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Tellgren, Roland
    Institutet för kemi, Uppsala Universitet.
    NEUTRON-DIFFRACTION STUDIES OF Y1-2XCAXTHXBA2CU3O7-DELTA WITH X-LESS-THAN=0.11991In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 185, p. 915-916Article in journal (Refereed)
    Abstract [en]

    We have made Rietveld refinements on neutron powder diffraction data from Y1-2xCaxThxBa2Cu3O7-delta samples with x < = 0.1. Only small changes in lattice distances are detected. Most noticeable are a flattening of the CuO-planes and a possible small increase in the distance between Cu(1) and the edge oxygen O(4). A comparison with the Y1-xCaxBa2Cu3O7-delta system is made.

  • 27.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Wen, TL
    Arrheniuslaboratoriet, Stockholms Universitet.
    Hegedüs, Zsolt
    Arrheniuslaboratoriet, Stockholms Universitet.
    Nygren, Mats
    Arrheniuslaboratoriet, Stockholms Universitet.
    CA AND PR SUBSTITUTION IN Y-BASED AND SM-BASED 1-2-3 COMPOUNDS1993In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 48, no 10, p. 7590-7597Article in journal (Refereed)
    Abstract [en]

    Substitution with equal amounts of Ca and Pr has been studied mainly in Y- and Sm-based 1:2:3 samples and with some results also for Nd-based samples. Structural and chemical analysis and measurements of the superconducting T(c) and the upper critical magnetic field were performed. It was found that Ca and Pr can be dissolved in the orthorhombic structure up to about 25 at. % each in both Y- and Sm-based samples while for larger concentrations, only Pr continued to enter into the 1:2:3 structure. The depression of T(c) with Ca-Pr doping was found to be linear in concentration in contrast to the accelerated decrease in samples doped with only Pr. The rate of depression of T(c) increased in the sequence Y-, Sm-, and Nd-based hosts. The results suggest that Ca-Pr doping isolates a characteristic Pr-impurity effect in 1:2:3 samples. The critical magnetic-field slopes of Y- and Sm-based samples were almost independent of Ca-Pr content in the cosolubility region while a strong decrease was observed for larger Pr content, similar to 1:2:3 samples doped with Pr only. These results suggest an almost-temperature-independent magnetic pair-breaking effect by Pr.

  • 28.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Rydh, Andreas
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Rapp, Östen
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Scaling of the vortex-liquid resistivity in optimally doped and oxygen-deficient YBa2Cu3O7-delta single crystals2001In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 63, no 18, p. 1845111-1845119Article in journal (Refereed)
    Abstract [en]

    The consequences of a recently proposed model [A. Rydh. O. Rapp. and M. Andersson. Phys. Rev. Lett. 83. 1850 (1999)] for the vortex-liquid resistivity close to a vortex liquid-to-glass transition are anal-zed in detail. We find a detailed quantitative agreement between the model and resistivity measurements on disordered, optimally doped YBa2Cu3O7-delta single crystals. For temperatures below the superconducting transition temperature. a scaling of all measured resistivity curves in magnetic field (0<B12 T) is obtained. Possible ways of slightly modifying the model in order to fully describe resistivity measurements on more anisotropic underdoped oxygen-deficient YBa2Cu3O7-delta single crystals are suggested. The physical interpretation of the model and its connection to other models of the vortex-liquid resistivity are discussed. in particular, we find close connections to vortex glass models and to a generalized Coulomb gas model.

  • 29.
    Andersson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Rydh, Andreas
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Vortex liquid resistivity in disordered YBa2Cu3O7-delta single crystals2000In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 341, p. 1239-1240Article in journal (Refereed)
    Abstract [en]

    The vortex solid-to-liquid transition line, T-g(B) and the linear resistivity in the vortex liquid of an optimally doped disordered YBa2Cu3O7-delta Single crystal is analyzed in detail. Our previously proposed description [Rydh, Rapp and Andersson, Phys.Rev.Lett. 83 (1999) 1850] is shown to quantitatively describe both T-g(B) and the vortex liquid resistivity above T-g using the same parameters. Furthermore, a comparison with the thermally activated behaviour usually employed to account for the resistivity in the vortex liquid is reported.

  • 30.
    Andersson, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Weurlander, Maria
    KTH, School of Industrial Engineering and Management (ITM), Learning.
    Peer review of laboratory reports for engineering students2018In: European Journal of Engineering Education, ISSN 0304-3797, E-ISSN 1469-5898, p. 1-12Article in journal (Refereed)
    Abstract [en]

    Here, we present a module to introduce student peer review of laboratoryreports to engineering students. Our findings show that students werepositive and felt that they had learnt quite a lot from this experience.The most important part of the module was the classification scheme.The scheme was constructed to mimic the way an expert would arguewhen making a fair judgement of a laboratory report. Hence, our resultsmay suggest that the success of the module design comes from activelyengaging students in work that is more related to ‘arguing like anexpert’ than to only supply feedback to peers, which in such a casewould implicate a somewhat new direction for feedback research. Forpractitioners, our study suggests that important issues to consider in thedesign are (i) a clear and understandable evaluation framework, (ii)anonymity in the peer-review process and (iii) a small external motivation.

  • 31.
    Anderssson, Magnus
    et al.
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Tellgren, Roland
    Institutet för kemi, Uppsala Universitet.
    NEUTRON-DIFFRACTION STUDIES OF INTERATOMIC DISTANCES IN THE Y1-2XCAXTHXBA2CU3O7-DELTA SYSTEM1992In: Solid State Communications, ISSN 0038-1098, E-ISSN 1879-2766, Vol. 81, no 5, p. 425-429Article in journal (Refereed)
    Abstract [en]

    Neutron diffraction studies have been performed for three samples of Y(1-2x)Ca(x)Th(x)Ba2Cu3O7-delta with 0 less-than-or-equal-to x less-than-or-equal-to 0.1. With increasing x, a decreased puckering of the Cu-O planes is found. Changes in copper oxygen distances are generally small. Evidence is found for a small increase in the distance between Cu(1) and O(4) (on the cell edge) with increased CaTh concentration. An increased oxygen disorder is observed at x = 0.1.

  • 32.
    Berglund, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Havtun, Hans
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Jerbrant, Anna
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    Wingård, Lasse
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Andersson, Magnus
    KTH, School of Engineering Sciences (SCI), Physics.
    Hedin, Björn
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID.
    Kjellgren, Björn
    KTH, School of Education and Communication in Engineering Science (ECE), Learning, Language and communication.
    THE PEDAGOGICAL DEVELOPERS INITIATIVE: SYSTEMATIC SHIFTS, SERENDIPITIES, AND SETBACKS2017In: 13th International CDIO Conference in Calgary, Canada, June 18-22, 2017, 2017Conference paper (Refereed)
    Abstract [en]

    Pedagogical projects have often, at KTH Royal Institute of Technology, as well as elsewhere, been initiated and managed by individual enthusiasts rather than dedicated teams. This generally decreases the possibility of successful implementation of more ambitious ideas, e.g., changing educational programs, implementing the CDIO syllabus, or strengthening the pedagogical development of larger parts of the faculty. To enable wider and more effective change, KTH top management therefore launched a universityencompassing three-year project in 2014, in which a group of highly motivated teachers from all schools at KTH were appointed part-time pedagogical developers (PDs). The PDs were given the task of promoting pedagogical development and facilitate cooperation and knowledge exchange among faculty members, as described in two previous papers at CDIO conferences. From 2017, the outcomes of this project are supposed to be integrated parts of the KTH line organization. The project has led to numerous actions, which would have been difficult to set in motion unless given the freedom in time to explore and to develop into a collective effort rather than a myriad of individual “stand-alone” examples. By addressing key areas for pedagogical development, our group of dedicated faculty have tried to surpass the suboptimal "lock-in" of strict individual reasoning and to deal with surfaced questions and relevant issues in a broader collective manner. A major insight confirmed by the project and its many sub-projects has indeed been the fundamental importance of collegial discussions and the creation of processes that facilitate and support teacher cooperation. We have also, through discussions with faculty at KTH, confirmed the need for clearly defined, tangible incentives for teachers, motivating them to participate in pedagogical development activities, even if this means less time left for the traditional pathway to rewards within academia, i.e. research. In this paper, we chart changes that have occurred in the educational practices at KTH by describing and discussing the project’s focus on pedagogical development of faculty, actual execution of changes in the engineering educations, lessons learned along the way, and visions yet to be realised.

  • 33.
    Berglund, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development. KTH.
    Havtun, Hans
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. KTH.
    Jerbrant, Anna
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management. KTH.
    Wingård, Lasse
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering. KTH.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Hedin, Björn
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID.
    Soulard, Juliette
    KTH, School of Electrical Engineering (EES).
    Kjellgren, Björn
    KTH, School of Education and Communication in Engineering Science (ECE), Learning, Language and communication.
    The pedagogical developers initiative - development, implementation and lessons learned from a systematic approach to faculty development2016In: Proceedings of the 12th International CDIO Conference, Turku University of Applied Sciences, Turku, Finland, June 12-16, 2016, Turku University , 2016, p. 497-508Conference paper (Refereed)
    Abstract [en]

    This paper presents a systematic, university--wide approach to creating an encompassing movement towards faculty development. In 2014, KTH Royal Institute of Technology launched the pedagogical developers initiative, appointing part--time pedagogical developers among teachers from all schools of KTH, to implement and strengthen good teaching and learning practices among faculty and students. They are teachers active in different educational programmes, with experience of, and interest in, pedagogical issues. In line with CDIO standard 10, the purpose of the pedagogical developers’ initiative is to facilitate cooperation and knowledge exchange between faculty members, and to establish communities of practice. The paper presents the activities, processes for developing these activities and preliminary results from the initiative’s second year, which focused much on supporting faculty development by putting into place a series of workshops, a format chosen for its combination of active community-building learning and time efficiency. The topics of the workshops emerged to meet faculty needs identified by the pedagogical developers during the first year. The workshops were created by smaller teams of pedagogical developers from different schools of KTH. This enabled a wide array of experiences and perspectives to be incorporated into the workshops. Main focuses of the workshops have been on creating internal discussions in dynamic communities of practice on specific subjects of interest, and on creating forums for exchange of ideas, open to the whole faculty. During Autumn 2015, the workshops have been offered as voluntary add-on parts of the basic course in teaching and learning offered to faculty at KTH. This first round of workshops generated a positive interest from teachers, and participant feedback indicates that they particularly appreciated the opportunity to work directly with their own courses and the opportunity to discuss pedagogical aspects with peers. 

  • 34.
    Berglund, Anders
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Havtun, Hans
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Johansson, Hans Bengt
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Jerbrant, Anna
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT).
    Hedin, Björn
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID.
    Soulard, Juliette
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Kjellgren, Björn
    KTH, School of Education and Communication in Engineering Science (ECE).
    The Pedagogical Developers Initiative – Changing Educational Practices and Strengthening CDIO skills2015In: Proceedings of the 11th International CDIO Conference, Chengdu, China, June 8-11 2015, 2015Conference paper (Refereed)
    Abstract [en]

    This paper put emphasis on change agents within the universities and how local initiatives can be systematically approached and ramped up. Rooted in the challenges and constraints that have been addressed in past educational program initiatives, the case consists of specific focus areas to leverage impact. Universities continuously strives to provide the best conditions for an inspiring and prosperous learning environment, and to provide educational programs with teaching of excellent educational quality. KTH is no exception and therefore the university management has initiated a pedagogical program starting in 2014. One of the first thing initiated within the framework of this pedagogical program is the creation of a group of 24 pedagogical developers.

    The focus for the pedagogical developers is to facilitate the opportunities for KTHs faculty to work together and create consensus on educational development in different teaching teams. This paper presents the University's pedagogical developers' initiative as a whole and how this has been outlined in detail to reach specific redesign targets. The School of Industrial Engineering and Management pedagogical group consists of five practicing teachers that besides this new role also engage heavily in various courses of the School's departments. Since the pedagogical initiative is aligned with several important CDIO aspects, e.g. the learning environment, formats of formative feedback, assessment and examination there is also importance to reassure this in the existing Master level programs.

    At KTH the five-year comprehensive Master of Science in Engineering programs concern distinct vocational educations in which the CDIO aspects are very important. At the same time the programs has been divided in a basic level (B.Sc. in Engineering) of three years and a advanced level (M.Sc.) of two years. This has for instance made it harder to align the progression between first cycle level and second cycle level regarding for instance the CDIO efforts (e.g. oral and written communication, teamwork). This paper will therefore discuss and enhance how the pedagogical programme, we as pedagogical developers, can support and strengthen the initiation and implementation of the CDIO aspects in the education.

  • 35. Björling, T.
    et al.
    Noréus, D.
    Jansson, K.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Leonova, E.
    Edén, M.
    Hålenius, U.
    Häussermann, U.
    SrAlSiH: A polyanionic semiconductor hydride2005In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 44, no 44, p. 7269-7273Article in journal (Refereed)
    Abstract [en]

    (Chemical Equation Presented) Stable and semiconducting: Polyanionic hydrides represent a new class of main-group-metal hydrides with unforeseen hydrogen-coordination environments. The hydrogen atom in SrAlSiH is attached exclusively to Al and forms part of a layered [AlHSi]2- polyanion (see figure). This material is the first narrow bandgap semiconductor hydride and combines the high thermal stability of saline hydrides with the air and moisture stability of interstitial transition-metal hydrides.

  • 36.
    Börjesson, Lars
    et al.
    Dept. Physics, Chalmers University of Technology.
    Phuong, H.V.
    Dept. Physics, Chalmers University of Technology.
    Jarlborg, Tomas
    Dept. de la Matière Condensée, University of Geneva.
    Andersson, Magnus
    KTH, Superseded Departments, Physics.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Ca-Th substitution in YBa2Cu3O7-delta: Raman scattering and calculation of the electron-phonon interaction1992In: Proceedings of the Joint Nordic Spring Meeting '92 / [ed] Per-Anker Lindgård, Roskilde, Denmark: Risø National Laboratory , 1992, p. 235-235Conference paper (Other academic)
  • 37.
    Espinosa-Arronte, Beatriz
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT), Material Physics.
    Scaling of vortex-liquid resistivity in high-Tc superconductors2005In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 71, no 2, p. 024507-Article in journal (Refereed)
    Abstract [en]

    Analysis of the in-plane resistivity of a Tl2Ba2CaCu2O8+delta thin film and of several oxygen-deficient YBa2Cu3O7-delta single crystals in magnetic fields 0less than or equal toBless than or equal to12 T applied along the crystallographic c axis were performed to study the resistive transition into the glassy state. The transition curves were scaled according to a modified model for the vortex-liquid resistivity, finding good scaling only for fields below a certain value B-0, consistent with the field-induced crossover between a three-dimensional and quasi-two-dimensional regime of the vortex fluctuations reported in several works. This indicates that for low fields the vortex state is in fact three dimensional and provides further support to a coherent description of the vortex-liquid resisitivity.

  • 38.
    Espinosa-Arronte, Beatriz
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    van der Beek, C. J.
    Laboratoire des Solides Irradiés, CNRS-UMR 7642 and CEA/DSM/DRECAM, Ecole Polytechnique, Palaiseau.
    Nikolaou, Marios
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Lidmar, Jack
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Wallin, Mats
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Fully anisotropic superconducting transition in ion-irradiated YBa2Cu3O7-delta with a tilted magnetic field2007In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, no 10, p. 100504-Article in journal (Refereed)
    Abstract [en]

    We consider the superconducting vortex solid-to-liquid transition in heavy ion-irradiated untwinned YBa2Cu3O7-delta single crystals in the case where the magnetic field direction does not coincide with that of the irradiation-induced linear columnar defects. For a certain range of angles, the resistivities measured in three orthogonal spatial directions vanish at the transition as three clearly different powers of reduced temperature. At previously known second-order phase transitions, scaling of physical quantities has either been isotropic or anisotropic in one direction. Thus, our findings yield evidence for a new type of critical behavior with fully anisotropic critical exponents.

  • 39.
    Espinosa-Arronte, Beatriz
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Djupmyr, Märit
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Scaling of the B-dependent resistivity for different orientations in Fe doped YBa2Cu3O7-[delta]2005In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 423, no 1-2, p. 69-73Article in journal (Refereed)
    Abstract [en]

    The angular dependence of a previously proposed modified model of the vortex glass transition has been investigated. The in-plane resistivity in an optimally oxygen doped YBa2Cu3O7-delta single crystal, doped with 1% Fe, was measured in fields up to 12 T applied with different orientations with respect to the crystallographic c-axis. The transition curves at all orientations were successfully scaled into one curve according to a scaling variable for the normalized resistivity. Characteristic parameters of the model, like the glass transition temperature and the magnetic field B-0, were measured at each orientation and were in good agreement with the expected values. These results show that the model proposed is valid also for fields applied outside the c-axis, giving further support to a more consistent description of the vortex liquid resistivity.

  • 40.
    Espinosa-Arronte, Beatriz
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Rapp, Östen
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Andersson, Magnus
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Scaling of the vortex liquid c-axis resistivity in underdoped YBa2Cu3O7-[delta]2004In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 408, p. 583-584Article in journal (Refereed)
    Abstract [en]

     The c-axis resistivity was measured in a twinned, underdoped YBa2Cu3O7-delta (YBCO) single crystal with T-c = 82.2 K. Resistive transition curves for fields Lip to 12 T applied along the c-axis were scaled to one function giving a good scaling. The scaling variable is the same as for the ab resistivity in optimally doped and underdoped YBCO single crystals [Phys. Rev. B 63 (2001) 184511]. This result provides further support to a coherent description of the vortex-liquid resistivity.

  • 41.
    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.

  • 42.
    Fischer, Oystein
    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.
    Andersson, Magnus
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Decroux, Michel
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Investigation of coupled DyBa2Cu3O7-(Y1-xPrx)Ba2Cu3O7 multilayer structures1994In: Superconducting Superlattices and Multilayers / [ed] Ivan Bozovic, Bellingham: SPIE - International Society for Optical Engineering, 1994, Vol. 2157, p. 134-141Conference paper (Refereed)
    Abstract [en]

    We report on the behavior of high Tc superconductor coupled multilayer structures in magnetic field perpendicular to the ab plane. In these structures the number N of superconducting layers in the sample has been systematically varied. We extract the activation energy for flux motion from resistive measurements of the superconducting transitions. For samples containing N 24 angstroms thick DyBa2Cu3O7 layers, each separated from the next by 96 angstroms of an (Y0.45Pr0.55)Ba2Cu3O7 alloy, we find that the activation energy U increases linearly with the number N of layers for N < 3 - 4, and then saturates. The linear increase of U is taken as an evidence that coupling through (Y0.45Pr0.55)Ba2Cu3O7 increases the correlated volume involved in the flux motion and thus U. For N = 3 stacked pancake vortices move rigidly and the vortex lattice is 2D. For N > 3 - 4 shear of the vortex lattice becomes important, the vortex lattice dimensionally crosses-over to 3D, and the activation energy saturates.

  • 43.
    Fivat, Patrice
    et al.
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Triscone, Jean-Marc
    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.
    Parallel and perpendicular field investigations of coupled high-Tc multilayer structures1994In: Superconducting Superlattices and Multilayers / [ed] Ivan Bozovic, Bellingham: SPIE - International Society for Optical Engineering, 1994, Vol. 2157, p. 192-198Conference paper (Refereed)
    Abstract [en]

    We report on the behavior of high Tc superconductors coupled multilayer structures in magnetic field parallel and perpendicular to the ab plane. These structures consist of N 24 angstroms thick DyBa2Cu3O7 layers, each separated from the next by 96 angstroms of an (Y0.45Pr0.55)Ba2Cu3O7 alloy. This alloy allows a coupling of the superconducting layers as demonstrated by measurements of the activation energies for flux motion U. For a N = 15 sample one finds, in perpendicular fields, that a correlated motion of pancake vortices occurs with a characteristic length of about 480 angstroms. Additionally, U is found to be proportional to logB at low fields while at higher fields a power law behavior is observed. In parallel field we find U to be field independent up to 1 T, suggesting that the vortices are trapped at low fields in the material where weak superconductivity is induced by proximity effect.

  • 44.
    Fivat, Patrice
    et al.
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Triscone, Jean-Marc
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Andersson, Magnus
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Obara, Haruhiko
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Fischer, Oystein
    Dept. de la Matière Condensée, University of Geneva, Geneva.
    Possible entanglement of the vortices in dyba2cu3O7 (y1-xprx)ba2cu3O7 coupled heterostructure1994In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 235, p. 2599-2600Article in journal (Refereed)
    Abstract [en]

    Thermally activated flux motion is studied in proximity coupled multilayers, containing a number N of 24 Angstrom thick DyBa2Cu3O7 layers separated by 96 Angstrom (or more) of(Y1-xPrx)Ba2Cu3O7 alloy (x=0.4, x=0.55). In contrast to ultra-thin decoupled layers, for which we find that the activation energy for flux motion U approximate to=logB (H//c), coupled samples show a cross-over to a power law behaviour U approximate to B–0.5 at magnetic field H*. This characteristic field depends on the anisotropy and decreases as N increases, a behaviour which can be understood in terms of the entanglement of the vortices, resulting in a relative increase of U due to the flux line crossing energy.

  • 45. Ghorbani, S. R.
    et al.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Rapp, Ö.
    The normal state Hall effect in Nd1-2xCaxMxBa2Cu3O7-delta (M = Pr, Th): Evidence for hole localization by disorder2005In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 424, no 04-mar, p. 159-168Article in journal (Refereed)
    Abstract [en]

    The transport properties of sintered samples of Nd1-2xCaxMxBa2Cu3O7-delta (M = Pr, Th) with 0 <= x <= 0.10 have been studied in the normal state by Hall effect measurements. The Hall coefficient at high temperature was almost constant for Ca-Pr while it increased with increasing Ca-Th doping concentration. The results for the Hall coefficient as a function of temperature and doping concentration were analyzed within two different models. A good agreement between models and data was obtained. On the basis of these models, it was inferred that Ca-Pr and Ca-Th doping introduce electronic disorder in the CUO2 planes. The localization tendency is driven by electronic disorder. This is the main reason for strong depression of the superconducting critical temperature in both alloys. It was found that the Hall angle is proportional to T-2 in the whole measured temperature range in Ca-Pr doped samples while there are deviations at high temperature in the Ca-Th doped series. In a phenomenological narrow band model, the conduction band was asymmetric for the pure sample and this asymmetry decreased with increasing Ca-Th doping while it was almost constant for Ca-Pr doped samples.

  • 46. Ghorbani, S. R.
    et al.
    Andersson, Magnus
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Rapp, Ö.
    Thermoelectric power of charge-neutral Nd1-2xCaxMxBa2Cu3O7-delta (M = Th and Pr): Evidence for different types of localization2002In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 66, no 10Article in journal (Refereed)
    Abstract [en]

    The superconducting T-c of Nd1-2xCaxMxBa2Cu3O7-delta (M=Th or Pr) is strongly depressed with increasing doping concentration in spite of the fact that these dopings are nominally charge neutral for small x. We have inquired into the reasons for this behavior by studies of the thermoelectric power S in sintered samples with x up to 0.1 and for temperatures from T-c up to room temperature. S(x,T) was analyzed in terms of two different semiempirical models, which assume the existence of a narrow electron band. In both models and for both dopings the bands broaden with increasing x and the tendency for localization increases. For Ca-Th doping this can be explained by weak electronic disorder. For Ca-Pr doping, the increase of electronic disorder is weaker, and the results indicate that charge localization in addition is important.

  • 47.
    Ghorbani, Shaban Reza
    et al.
    KTH, Superseded Departments, Physics.
    Andersson, Magnus
    KTH, Superseded Departments, Physics.
    Lundqvist, Pieter
    KTH, Superseded Departments, Physics.
    Valldor, M.
    Arrheniuslaboratoriet, Stockholms Universitet.
    Rapp, Östen
    KTH, Superseded Departments, Physics.
    Thermoelectric power and resistivity of Nd1-xCaxBa2Cu3Oy and Nd1-xLaxBa2Cu3Oy2000In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 339, no 4, p. 245-252Article in journal (Refereed)
    Abstract [en]

    The structural and transport properties of Nd1-xCaxBa2Cu3Oy (x = 0.0, 0.03, 0.06, and 0.10) and Nd1-xLax- Ba2Cu3Oy. (x nominally 0.0, 0.05, 0.10, and 0.15) have been studied by X-ray powder diffraction, electrical resistivity, and thermoelectric power measurements. In both series, the a- and b-axis lattice parameters decrease with increasing doping while the c-axis lattice parameter increases. The transport properties suggest improved metallic behaviour with increasing Ca doping in contrast to La doping. An anomalous sharp peak in the thermoelectric power close to T-c was observed, which depended on the doping content. We analysed the thermoelectric power as a function of temperature with a two-band model with an additional linear T term. An excellent agreement between model and data was obtained.

  • 48.
    Ghorbani, Shaban Reza
    et al.
    Department of Physics, Tarbiat Muallem University of Sabzevar, Iran.
    Andersson, Magnus
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Rapp, Östen
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Disorder Driven Localization in Charge Neutrally Doped 123 Superconductors2006In: Low Temperature Physics / [ed] Takano, Y; Hershfield, SP; Hirschfeld, PJ; Goldman, AM, 2006, Vol. 850, p. 439-440Conference paper (Refereed)
    Abstract [en]

    Charge neutral dopings with equal amounts of CaTh or CaPr on rare earth site in Nd-123 have been investigated by studies of the normal state electrical resistivity, p, the Seebeck coefficient S, and the Hall coefficient R-H. In spite of comparable rates of depression of the superconducting T, significant differences are observed in the doping concentration dependence of p, S, and RH between the two dopings. These results are discussed in terms of disorder induced localization.

  • 49.
    Ghorbani, Shaban Reza
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Andersson, Magnus
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Rapp, Östen
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Neutron diffraction studies of Nd1-xPrxBa2Cu3O7-delta: Evidence for hole localization2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, no 1, p. 145031-Article in journal (Refereed)
    Abstract [en]

    Sintered samples of Nd1-xPrxBa2Cu3O7-delta with x=0, 0.05, 0.10, 0.15, 0.20, and 0.30 have been studied by neutron diffraction, x-ray diffraction, and resistivity measurements. Sample stoichiometry was carefully checked. Atomic distances within the unit cell and the oxygen content were shown to be almost independent of Pr doping. Bond valence sums (BVSs) were calculated from the neutron diffraction data assuming either a constant valence or a mixed valence for Cu and Pr ions. The planar Cu2 valence is independent of Pr doping and the chain Cu1 valence is roughly constant, while the hole concentration in the planes and chains decrease with increasing Pr doping for both BVS calculation methods. All together, this indicates that hole localization on the Nd(Pr) site is a main reason for the decrease of the hole concentration in the planes. A consistent relation between the hole concentration in the planes calculated from the constant valence method and the depression of the critical temperature is also obtained, both for Pr-doped Nd-123 and for Y(Pr)-123 studied previously.

  • 50.
    Ghorbani, Shaban Reza
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Andersson, Magnus
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Rapp, Östen
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Normal state Hall effect in Nd1-xCaxBa2Cu3O7-delta: competition between added charge and disorder2003In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 390, no 2, p. 160-166Article in journal (Refereed)
    Abstract [en]

    The transport properties of sintered samples of Nd1-xCaxBa2CU3O7-delta with 0 less than or equal to x less than or equal to 0.20 have been studied in the normal state by Hall resistivity measurements. The Hall coefficient, R-H(x, T) was well described in terms of two different models. In a phenomenological narrow band model, the conduction band width became narrower with increasing Ca concentration while the density of states band width decreased slightly. A competition between two effects (i) added charge, and (ii) disorder introduced into the CuO2 planes by doping, could be the main reason for the observed small decrease of the band widths. In the Anderson model, the temperature dependent part of the Hall angle was independent of hole concentration and disorder while the temperature independent part increased linearly with increasing Ca content. The results in both models support that Ca introduces disorder in the CuO2 planes.

12 1 - 50 of 89
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • 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