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Author Nieva, G.; Osquiguil, E.; Guimpel, J.; Maenhoudt, M.; Wuyts, B.; Bruynseraede, Y.; Maple, M.B.; Schuller, I.K.
Title Photoinduced enhancement of superconductivity Type Journal Article
Year 1992 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume 60 Issue (up) 17 Pages 2159-2161
Keywords
Abstract We show clear and conclusive experimental evidence for the enhancement of superconductivity in GdBa2Cu3Ox and YBa 2Cu3Ox thin films by photoexcitation. Upon laser illumination the critical temperature increases while the resistivity of the material decreases. The relaxation back to the original state is very slow, of the order of days at room temperature. The existence of this effect opens the possibility of fabricating weak-link devices with in situ tunable superconducting characteristics.
Address Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, B3001 Leuven, Belgium
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ISSN 00036951 (ISSN) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 61; Export Date: 17 April 2009; Source: Scopus; doi: 10.1063/1.107069; Language of Original Document: English; Correspondence Address: Nieva, G.; Physics Department-0319; University of California-San Diego San Diego, CA 92093-0319, United States Approved no
Call Number BT @ osquigui @ Serial 404
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Author Neerinck, D.; Temst, K.; Baert, M.; Osquiguil, E.; Van Haesendonck, C.; Bruynseraede, Y.; Gilabert, A.; Schuller, I.K.
Title Transition in the flux lattice of artificially layered superconductors Type Journal Article
Year 1991 Publication Physical Review Letters Abbreviated Journal
Volume 67 Issue (up) 18 Pages 2577-2580
Keywords
Abstract We report a novel magnetic-field dependence of the critical-current density Jc in artificially grown Ge/Pb superlattices. In these layered structures Jc exhibits an unexpected minimum as a function of perpendicular applied field, unlike any ever observed in other superconductor systems. The systematic evolution of this minimum as a function of layer thicknesses, temperature and pinning strength is related to either flux-lattice decoupling or melting.
Address Department of Physics, University of California, San Diego, La Jolla, CA 92093-0319
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ISSN 00319007 (ISSN) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 7; Export Date: 17 April 2009; Source: Scopus; doi: 10.1103/PhysRevLett.67.2577; Language of Original Document: English; Correspondence Address: Neerinck, D.; Laboratorium voor Vaste Stof-Fysika en Magnetisme; Katholieke Universiteit Leuven B-3001 Leuven, Belgium Approved no
Call Number BT @ osquigui @ Serial 411
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Author Gao, Z.X.; Osquiguil, E.; Maenhoudt, M.; Wuyts, B.; Libbrecht, S.; Bruynseraede, Y.
Title 3D-2D dimensional crossover in YBa2Cu3O7 films Type Journal Article
Year 1993 Publication Physical Review Letters Abbreviated Journal
Volume 71 Issue (up) 19 Pages 3210-3213
Keywords
Abstract We show that, in fully oxidized YBa2Cu3O7 c-axis oriented films, the changes induced in the angular and field dependence of the magnetoresistivity ?ab by increasing the temperature towards Tc are similar to those caused by a lowering in oxygen content. This remarkable behavior can be interpreted as due to a crossover from a three-dimensional to a two-dimensional system as T approaches Tc. Moreover, our critical current data mimic the behavior observed by Qi Li et al. in YBa2Cu3O7/(PrxY1-x)Ba2Cu3O7 multilayers, suggesting the possibility that chain planes are superconducting.
Address Laboratorium Voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 00319007 (ISSN) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 7; Export Date: 17 April 2009; Source: Scopus; doi: 10.1103/PhysRevLett.71.3210; Language of Original Document: English; Correspondence Address: Gao, Z.X.; Laboratorium Voor Vaste Stof-Fysika en Magnetisme; Katholieke Universiteit Leuven; Celestijnenlaan 200D B-3001 Leuven, Belgium Approved no
Call Number BT @ osquigui @ Serial 400
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Author Neerinck, D.; Temst, K.; Baert, M.; Osquiguil, E.; Van Haesendonck, C.; Bruynseraede, Y.; Gilabert, A.; Schuller, I.K.
Title Softening of the flux line lattice in Ge/Pb multilayers Type Journal Article
Year 1992 Publication Superconductor Science and Technology Abbreviated Journal
Volume 5 Issue (up) 1S Pages
Keywords
Abstract The authors measured the critical current density Jc of artificially grown Ge/Pb multilayers as a function of the magnetic field H perpendicular to applied perpendicular to the layers. In these layered structures Jc(Hperpendicular to) rapidly drops to a pronounced minimum at a field H*perpendicular to, then increases through a broad maximum and finally decays to zero at H c2 perpendicular to. The systematic evolution of this minimum as a function of temperature, layer thickness and pinning strength allows us to conclude that this peculiar behavior is due to a thermally driven softening of the flux line lattice which can be related either to a magnetic decoupling or a melting of the vortex structure.
Address Lab. voor Vaste Stof-Fysika en Magn., Katholieke Univ., Leuven, Belgium
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Series Editor Series Title Abbreviated Series Title
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ISSN 09532048 (ISSN) ISBN Medium
Area Expedition Conference
Notes Export Date: 17 April 2009; Source: Scopus; Art. No.: 029; doi: 10.1088/0953-2048/5/1S/029; Language of Original Document: English; Correspondence Address: Neerinck, D.; Lab. voor Vaste Stof-Fysika en Magn.; Katholieke Univ. Leuven, Belgium Approved no
Call Number BT @ osquigui @ Serial 408
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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 (up) 2 Pages 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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Series Editor Series Title Abbreviated Series Title
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ISSN 01631829 (ISSN) ISBN Medium
Area Expedition Conference
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 Nieva, G.; Osquiguil, E.; Guimpel, J.; Maenhoudt, M.; Wuyts, B.; Bruynseraede, Y.; Maple, M.B.; Schuller, I.K.
Title Photoinduced changes in the transport properties of oxygen-deficient YBa2Cu3Ox Type Journal Article
Year 1992 Publication Physical Review B Abbreviated Journal
Volume 46 Issue (up) 21 Pages 14249-14252
Keywords
Abstract We show that illumination of oxygen-deficient metallic YBa2Cu3Ox films produces a change in the Hall coefficient, an increase in the critical temperature, and a decrease in the electrical resistivity. These changes relax to equilibrium with characteristic times of the order of days, and are due to variations in both the carrier density and mobility. The relaxation times are of the same order of magnitude as the ones measured in nonilluminated oxygen-deficient films immediately after quenching.
Address Laboratory for Solid State Physics and Magnetism, University of Leuven, B3001 Leuven, Belgium
Corporate Author Thesis
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 01631829 (ISSN) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 62; Export Date: 17 April 2009; Source: Scopus; doi: 10.1103/PhysRevB.46.14249; Language of Original Document: English; Correspondence Address: Nieva, G.; Physics Department; University of California(enSan Diego San Diego, CA 92093-0319, United States Approved no
Call Number BT @ osquigui @ Serial 407
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Author Libbrecht, S.; Osquiguil, E.; Bruynseraede, Y.
Title Influence of field inhomogeneity on the magnetization of YBCO films Type Journal Article
Year 1994 Publication Physica C: Superconductivity and its applications Abbreviated Journal Phys C Supercond Appl
Volume 225 Issue (up) 3-4 Pages 337-345
Keywords Magnetization; Superconducting films; SQUID magnetometers; Superconducting ceramics; YBCO superconductors; High temperature superconductors
Abstract DC magnetization data of superconducting thin YBCO films, measured by means of a magnetometer in which the sample is pulled through a set of pick-up coils, are often calculated from pick-up signals which clearly deviate from the ideal response. We show how these signal distortions influence the values obtained for the magnetization, and present a simple model that enables one to simulate the temperature dependence of these distorted pick-up signals, in the case of low-field magnetization measurements. The model is based on the magnetic field inhomogeneity of the magnetometer, in combination with the hysteretic magnetization of the superconducting sample. Optimum values for the model parameters are derived and discussed.
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
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 09214534 (ISSN) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 11; Export Date: 17 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: Bruynseraede, Y.; Laboratorium voor Vaste Stof-Fysika en Magnetisme; Katholieke Universiteit Leuven; Celestijnenlaan 200 D B-3001 Leuven, Belgium Approved no
Call Number BT @ osquigui @ Serial 394
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Author Wuyts, B.; Osquiguil, E.; Maenhoudt, M.; Libbrecht, S.; Gao, Z.X.; Bruynseraede, Y.
Title Relation between the Hall angle slope and the carrier density in oxygen-depleted YBa2Cu3Ox films Type Journal Article
Year 1994 Publication Physica C: Superconductivity and its applications Abbreviated Journal Phys C Supercond Appl
Volume 222 Issue (up) 3-4 Pages 341-348
Keywords Doping (additives); Electric conductivity; Hall effect; Mathematical models; Thermal effects; Thin films; Transport properties; Yttrium compounds; Carrier density; Hall angle slope; Oxygen content; Zero temperature intercept; Superconducting films
Abstract A detailed study of the Hall angle cot?H in YBa2Cu3Ox epitaxial thin films with various oxygen contents clearly shows the existence of a linear relation between the slope of cot?H versus T2 and the carrier density. The zero-temperature intercept C=cot?H(T=0 K) and the mobility at room temperature change substantially for an oxygen content x?6.6, indicating that both effects are closely related.
Address Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium
Corporate Author Thesis
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 09214534 (ISSN) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 8; Export Date: 17 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: Bruynseraede, Y.; Laboratorium voor Vaste Stof-Fysika en Magnetisme; Katholieke Universiteit Leuven; Celestijnenlaan 200 D B-3001 Leuven, Belgium Approved no
Call Number BT @ osquigui @ Serial 395
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Author Wuyts, B.; Gao, Z.X.; Libbrecht, S.; Maenhoudt, M.; Osquiguil, E.; Bruynseraede, Y.
Title Growth of particle-free YBa2Cu3O7 films by off-axis sputtering Type Journal Article
Year 1992 Publication Physica C: Superconductivity and its applications Abbreviated Journal Phys C Supercond Appl
Volume 203 Issue (up) 3-4 Pages 235-239
Keywords Copper oxides; Film growth; Film preparation; Magnetrons; Particles (particulate matter); Sputter deposition; Substrates; Superconductivity; Thin films; Yttrium compounds; Critical current density; Off axis single target magnetron sputtering; Particle free superconducting films; Yttrium barium copper oxides; Superconducting films
Abstract The preparation of good YBa2Cu3O7 thin films is often hindered by the production of non-stoichiometric particles which degrade the superconducting properties of the layer. A systematic study of films prepared by off-axis single target magnetron sputtering shows that the presence of copper-rich particles dramatically decreases the critical current density but does not affect the critical temperature. The formation of these particles can be avoided by carefully adjusting the position of the substrate with respect to the target. Films without off-stoichiometric particles have excellent superconducting properties.
Address Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium
Corporate Author Thesis
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 09214534 (ISSN) ISBN Medium
Area Expedition Conference
Notes Cited By (since 1996): 10; Export Date: 17 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: Wuyts, B.; Laboratorium voor Vaste Stof-Fysika en Magnetisme; Katholieke Universiteit Leuven; Celestijnenlaan 200 D B-3001 Leuven, Belgium Approved no
Call Number BT @ osquigui @ Serial 403
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Author Osquiguil, E.; Gao, Z.X.; Maenhoudt, M.; Wuyts, B.; Libbrecht, S.; Bruynseraede, Y.
Title YBa2Cu3Ox: A natural multilayer system with tunable anisotropy Type Journal Article
Year 1993 Publication Journal of Physics: Condensed Matter Abbreviated Journal
Volume 5 Issue (up) 33 A Pages
Keywords
Abstract The authors report on magnetoresistivity rho ab( theta ,H,T) measurements below Tc in YBa2Cu3Oxn films with differing oxygen content x. The observed variations in the angular and field dependence of rho ab with reduced x indicate a gradual dimensional crossover from an anisotropic 3D to a quasi-2D behaviour. The increasing anisotropy is related to a decrease of the coupling between the Cu2O2 bilayers when oxygen is removed from the Cu1Ox chain-planes.
Address Lab. voor Vaste Stof-Fysika en Magnetisme, Katholieke Univ. Leuven, Belgium
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 09538984 (ISSN) ISBN Medium
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Notes Cited By (since 1996): 1; Export Date: 17 April 2009; Source: Scopus; Art. No.: 145; doi: 10.1088/0953-8984/5/33A/145; Language of Original Document: English; Correspondence Address: Osquiguil, E.; Lab. voor Vaste Stof-Fysika en Magnetisme; Katholieke Univ. LeuvenBelgium Approved no
Call Number BT @ osquigui @ Serial 399
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