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Author Neerinck, D.; Temst, K.; Baert, M.; Osquiguil, E.; Van Haesendonck, C.; Bruynseraede, Y.; Gilabert, A.; Schuller, I.K.
Title Thermally induced transition in the vortex lattice of Ge/Pb multilayers Type Journal Article
Year 1991 Publication Physica C: Superconductivity and its applications Abbreviated Journal Phys C Supercond Appl
Volume 185-189 Issue PART 3 Pages (down) 2061-2062
Keywords Germanium And Alloys; Lead And Alloys; Superconducting Films; Thermal Effects; Critical Currents; Multilayers; Metallic Films
Abstract We report on a novel magnetic field dependence of the critical current density of M.B.E. grown Ge/Pb insulator/superconductor multilayers. When the magnetic field is applied perpendicular to the layers, the critical current density Jc drops to a minimum, followed by a broad maximum before finally decaying monotonously to zezero with increasing magnetic field. The dependence of this effect on pinning strength, temperature, and layer thickness suggests either a thermally driven coupling/decoupling transition, or melting of the vortex lattice.
Address Physics Department, University of California, San Diego, CA 92093-0319, United States
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ISSN 09214534 (ISSN) ISBN Medium
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Notes Export Date: 17 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: Neerinck, D.; Laboratorium voor Vaste Stof-Fysika en Magnetisme; K.U. Leuven B-3001 Leuven, Belgium Approved no
Call Number BT @ osquigui @ Serial 412
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Author Griessen, R.; Wen Hai-Hu; Van Dalen, A.J.J.; Dam, B.; Rector, J.; Schnack, H.G.; Libbrecht, S.; Osquiguil, E.; Bruynseraede, Y.
Title Evidence for mean free path fluctuation induced pinning in YBa2Cu3O7 and YBa2Cu4O8 films Type Journal Article
Year 1994 Publication Physical Review Letters Abbreviated Journal
Volume 72 Issue 12 Pages (down) 1910-1913
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Abstract The critical current jc and the pinning energy Uc have been determined for three types of yttrium-based superconducting films from current js and dynamic relaxation Q=d lnjs/d ln(dB/dt) data by means of the generalized inversion scheme. For B<2 T and T<80 K the temperature dependence of jc and Uc for all films is found to be in excellent agreement with a model of single vortices pinned by randomly distributed weak pinning centers via spatial fluctuations of the charge carrier mean free path. Pinning due to spatial fluctuations of Tc is not observed.
Address Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, 4001-Leuven, Belgium
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ISSN 00319007 (ISSN) ISBN Medium
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Notes Cited By (since 1996): 103; Export Date: 17 April 2009; Source: Scopus; doi: 10.1103/PhysRevLett.72.1910; Language of Original Document: English; Correspondence Address: Griessen, R.; Faculty of Physics and Astronomy; Free University 1081 HV Amsterdam, Netherlands Approved no
Call Number BT @ osquigui @ Serial 389
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Author Osquiguil, E.; Maenhoudt, M.; Wuyts, B.; Bruynseraede, Y.
Title Controlled preparation of oxygen deficient YBa2Cu 3Ox films Type Journal Article
Year 1992 Publication Applied Physics Letters Abbreviated Journal
Volume 60 Issue 13 Pages (down) 1627-1629
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Abstract We describe a simple method based on the oxygen pressure-temperature phase diagram to prepare oxygen deficient YBa2Cu3Ox thin films. Systematic critical temperature and x-ray diffraction experiments clearly show that films with different oxygen contents (6.6?x?7) are obtained in a controlled, reproducible, and reversible way.
Address Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium
Corporate Author Thesis
Publisher Place of Publication Editor
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 00036951 (ISSN) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 38; Export Date: 17 April 2009; Source: Scopus; doi: 10.1063/1.107221; Language of Original Document: English; Correspondence Address: Osquiguil, E.; Laboratorium voor Vaste Stof-Fysika en Magnetisme; Katholieke Universiteit Leuven; Celestijnenlaan 200 D B-3001 Leuven, Belgium Approved no
Call Number BT @ osquigui @ Serial 405
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Author Martin, J.I.; Wuyts, B.; Maenhoudt, M.; Osquiguil, E.; Vicent, J.L.; Moshchalkov, V.V.; Bruynseraede, Y.
Title Sign reversal of the flux flow Hall effect in oxygen deficient YBa2Cu3Ox films Type Journal Article
Year 1994 Publication Physica C: Superconductivity and its applications Abbreviated Journal Phys C Supercond Appl
Volume 235-240 Issue PART 2 Pages (down) 1451-1452
Keywords
Abstract The Hall effect of high temperature superconductors has been reported to slow in some cases a striking sign reversal near Tc, the origin of which is not yet fully understood. We report on measurements of the Hall effect in the mixed state of oxygen deficient YBa2Cu3Ox thin films, for 7?
Address Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
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ISSN 09214534 (ISSN) ISBN Medium
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Notes Export Date: 17 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: Martin, J.I.; Dpto. Fisica de Materiales; Facultad de Ciencias Fisicas; Universidad Complutense 28040 Madrid, Spain Approved no
Call Number BT @ osquigui @ Serial 386
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Author Wuyts, B.; Maenhoudt, M.; Libbrecht, S.; Gao, Z.X.; Osquiguil, E.; Moshchalkov, V.V.; Bruynseraede, Y.
Title Linear relation between the Hall angle slope and the carrier density in YBa2Cu3Ox films Type Journal Article
Year 1994 Publication Physica C: Superconductivity and its applications Abbreviated Journal Phys C Supercond Appl
Volume 235-240 Issue PART 2 Pages (down) 1369-1370
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Abstract A universal relation cot?H??{variant}/RHB = ?T2 + C for the Hall angle ?H has been experimentally observed served in a wide variety of high-Tc systems. In contrast to the linear temperature dependence of the resistivity ?{variant} or the inverse Hall coefficient R-1H, the T2-dependence of cot?H remains valid in under- and overdoped systems. We present a systematic study of cot?H(T) in oxygen deficient epitaxial YBa2Cu3Ox thin films. We find evidence for a linear relation between ?, the slope of cot?H versus T2, and the carrier concentration. Moreover, we find a steep increase in the intercept C = cot?H (T = 0) below x ? 6.6.
Address Laboratorium voor Vaste-Stoffysika en Magnetisme, Katholieke Universiteit Leuven Celestijnenlaan 200D, B-3001 Leuven, Belgium
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Series Editor Series Title Abbreviated Series Title
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ISSN 09214534 (ISSN) ISBN Medium
Area Expedition Conference
Notes Export Date: 17 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: Wuyts, B.; Laboratorium voor Vaste-Stoffysika en Magnetisme; Katholieke Universiteit Leuven Celestijnenlaan 200D B-3001 Leuven, Belgium Approved no
Call Number BT @ osquigui @ Serial 392
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Author Van Dalen, A.J.J.; Griessen, R.; Libbrecht, S.; Bruynseraede, Y.; Osquiguil, E.
Title Quantum creep and pinning properties of oxygen-deficient YBa2Cu3Oxn films Type Journal Article
Year 1996 Publication Physical Review B – Condensed Matter and Materials Physics Abbreviated Journal Phys. Rev. B Condens. Matter Mater. Phys.
Volume 54 Issue 2 Pages (down) 1366-1381
Keywords
Abstract A high sensitivity capacitance torquemeter has been used for a comprehensive investigation of the induced current densities and dynamic relaxation rates in a YBa2Cu3Oxn film with nominal oxygen content varying between xn=6.55 and xn=7.0. The dynamic relaxation rate Q does not extrapolate to zero at T=0 K, indicating the presence of quantum creep. By changing the oxygen content of the film it is possible to investigate the relation between the quantum creep rate Q(0) and the normal-state resistivity pn(0) at low temperature. Although Q(0) increases monotonically with pn, it is found that Q(0) is not proportional to pn(0), in contrast to the predictions of a theory based on dissipative tunneling of collectively pinned single vortices [Blatter et al., Rev. Mod. Phys. 66, 1125 (1994)]. The experimental results imply that in YBa2Cu3O7 quantum creep takes place in a transition regime between Hall tunneling and dissipative tunneling. For lower oxygen contents the quantum creep regime moves towards the dissipative limit. For each oxygen content the characteristic pinning energy Uc(0) at T=0 is obtained by a linear extrapolation to T= 0 K of the T/Q versus T curves. The critical current density jc at T=0 is determined independently by a linear extrapolation of the measured Injs versus T curves. A power-law relation Uc(0)?[jc(0)]p with p? 0.5 is found, indicating single vortex pinning at higher temperatures. This is confirmed by a detailed analysis of the measured current densities and relaxation rates by means of the generalized inversion scheme developed by Schnack et al. [Phys. Rev. B 48, 13 178 (1993)]. For xn? 6.6 at Be= 0.6 T and for xn? 6.7 at Be= 2.0 T the calculated temperature dependence of jc and Uc agrees remarkably well with a model based on three-dimensional single vortex pinning caused by spatial fluctuations in the charge carrier mean free path. At lower oxygen contents and higher magnetic-fields the agreement gradually breaks down due to the increasing importance of thermal fluctuations.
Address Montell Polyolefins, Centre Ricerche G. Natta, P. Le P. to G. Donegani 12, 44100 Ferrara, Italy
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ISSN 01631829 (ISSN) ISBN Medium
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Notes Cited By (since 1996): 27; Export Date: 17 April 2009; Source: Scopus; CODEN: PRBMD; Language of Original Document: English; Correspondence Address: Van Dalen, A.J.J.; Materials Science Division; Argonne National Laboratory Argonne, IL 60439, United States; References: Mota, A.C., Pollini, A., Visani, P., M Approved no
Call Number BT @ osquigui @ Serial 383
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Author Fullerton, E.E.; Kelly, D.M.; Guimpel, J.; Schuller, I.K.; Bruynseraede, Y.
Title Roughness and giant magnetoresistance in Fe/Cr superlattices Type Journal Article
Year 1992 Publication Physical Review Letters Abbreviated Journal Prl
Volume 68 Issue 6 Pages (down) 859
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Abstract
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Publisher American Physical Society Place of Publication Editor
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Call Number BT @ jguimpel @ 10.1103/PhysRevLett.68.859 Serial 614
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Author Gao, Z.X.; Heyvaert, I.; Wuyts, B.; Osquiguil, E.; Haesendonck, C.V.; Bruynseraede, Y.
Title Evidence for a “brick wall” microstructure in epitaxial YBa 2Cu3Ox films Type Journal Article
Year 1994 Publication Applied Physics Letters Abbreviated Journal
Volume 65 Issue 6 Pages (down) 770-772
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Abstract We have measured the in-plane (ab plane) critical current density J c in sputtered, c-axis oriented YBa2Cu3O x films as a function of the oxygen content x. The important reduction of Jc with decreasing x can be explained in terms of a “brick wall” microstructure, where the critical current density is dominated by the coupling strength (along the c axis) between the superconducting CuO 2 planes. Scanning tunneling microscopy images of the film surfaces are consistent with the presence of the brick wall structure, which apparently results from the overlap between terraces belonging to adjacent spiral-shaped islands.
Address Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
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Series Editor Series Title Abbreviated Series Title
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ISSN 00036951 (ISSN) ISBN Medium
Area Expedition Conference
Notes Export Date: 17 April 2009; Source: Scopus; doi: 10.1063/1.112225; Language of Original Document: English; Correspondence Address: Gao, Z.X.; Laboratorium voor Vaste-Stoffysica en Magnetisme; Katholieke Universiteit Leuven; Celestijnenlaan 200D B-3001 Leuven, Belgium Approved no
Call Number BT @ osquigui @ Serial 391
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Author Osquiguil, E.; Maenhoudt, M.; Wuyts, B.; Bruynseraede, Y.; Lederman, D.; Nieva, G.; Guimpel, J.; Schuller, I.K.
Title Photoexcitation effects in YBa2Cu3Ox Type Journal Article
Year 1993 Publication Journal of Alloys and Compounds Abbreviated Journal J Alloys Compd
Volume 195 Issue C Pages (down) 667-670
Keywords Barium compounds; Ceramic materials; Copper oxides; High temperature superconductors; Oxides; Photoelectricity; Yttrium compounds; C-axis oriented films; Photoexcitation effects; Photoinduced phenomena; Yttrium barium cuprates; Superconducting films
Abstract We show through photoexcitation experiments carried out on YBa2Cu3Ox c-axis oriented films that photoinduced phenomena are not restricted to insulating samples. Superconducting films with critical temperatures varying between 2 K and 40 K show a clear enhancement of the superconducting transition after illumination. The increase in Tc is accompanied by a corresponding decrease in the resistivity ?, and an increase in the Hall coefficient RH, indicative of an increased carrier density. Furthermore, the carrier mobility is also affected by illumination.
Address Physics Department – 0319, University of California – San Diego, La Jolla, CA 92093-0319, United States
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ISSN 09258388 (ISSN) ISBN Medium
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Notes Cited By (since 1996): 4; Export Date: 17 April 2009; Source: Scopus; CODEN: JALCE; Language of Original Document: English; Correspondence Address: Osquiguil, E.; Laboratorium voor Vaste Stof-Fysika en Magnetisme; Katholieke Universiteit Leuven B-3001 Leuven, Belgium Approved no
Call Number BT @ osquigui @ Serial 401
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Author Lederman, D.; Hasen, J.; Schuller, I.K.; Osquiguil, E.; Bruynseraede, Y.
Title Photoinduced superconductivity and structural changes in high temperature superconducting films Type Journal Article
Year 1994 Publication Applied Physics Letters Abbreviated Journal
Volume 64 Issue 5 Pages (down) 652-654
Keywords Annealing; Electric conductivity measurement; Lighting; Oxygen; Praseodymium compounds; Quenching; Semiconducting films; Structure (composition); Superconductivity; Thermal effects; Thin films; Yttrium compounds; Contraction; Oxygen vacancy; Photoinduced superconductivity; Stoichiometry; Superconducting critical temperature; High temperature superconductors
Abstract The illumination of PryGd1-yBa2Cu 3Ox semiconducting and superconducting thin films increases their critical temperatures and decreases their normal state resistivities if and only if the films are oxygen deficient. Moreover, these changes are enhanced near the Pr-induced metal-insulator transition. Light also causes a contraction of the c-axis in YBa2Cu3Ox which is correlated with the observed photoinduced resistivity changes. These changes are similar to those observed when oxygen-deficient YBa 2Cu3Ox is enriched with oxygen or annealed at room temperature after quenching from high temperatures.
Address Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium
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ISSN 00036951 (ISSN) ISBN Medium
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Notes Cited By (since 1996): 37; Export Date: 17 April 2009; Source: Scopus; doi: 10.1063/1.111078; Language of Original Document: English; Correspondence Address: Lederman, D.; Physics Department; University of California-San Diego San Diego, CA 92093-0319, United States Approved no
Call Number BT @ osquigui @ Serial 390
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