| Records |
| Author |
Libbrecht, S.; van Dalen, A.J.J.; Wuyts, B.; Maenhoudt, M.; Gao, Z.X.; Osquiguil, E.; Griessen, R.; Bruynseraede, Y. |
| Title |
Magnetic properties of oxygen deficient Yba2Cu3Ox thin films |
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Journal Article |
| Year |
1994 |
Publication |
Physica C: Superconductivity and its applications |
Abbreviated Journal |
Phys C Supercond Appl |
| Volume |
235-240 |
Issue |
PART 5 |
Pages |
2889-2890 |
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| Abstract |
We have invesitgated several superconducting properties of oxygen defiecient YBa2Cu3Ox thin films, with oxygen contents ranging from x = 6.55 to x = 7. By means of torque magnetometry, the temperature dependence of the superconducting current dendity js and relaxation rate of the magnetization Q is measured in an (almost perpendicular) applied magnetic induction of 0.6 T. As the oxygen content is reduced, js decreases, whereas Q increases. Both properties are influenced by the decreased dpoing level as well as the enhanced anisotropy of oxygen depleted YBa2Cu3Ox. Using the Generalixed Inversion Scheme derived by Schnak et al. we obtain the current dependence of the activation energy U(f). We show that U(j) is lowered when the oxygen content is reduced. |
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09214534 (ISSN) |
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Export Date: 17 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: Libbrecht, S.; Laboratorium voor Vaste-Stoffysika en Magnetisme; Katholieke Universiteit B-3001 Leuven, Belgium |
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BT @ osquigui @ |
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387 |
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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 |
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Journal Article |
| Year |
1994 |
Publication |
Physical Review Letters |
Abbreviated Journal |
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| Volume |
72 |
Issue |
12 |
Pages |
1910-1913 |
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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. |
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Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, 4001-Leuven, Belgium |
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00319007 (ISSN) |
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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 |
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BT @ osquigui @ |
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389 |
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Lederman, D.; Hasen, J.; Schuller, I.K.; Osquiguil, E.; Bruynseraede, Y. |
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Photoinduced superconductivity and structural changes in high temperature superconducting films |
Type |
Journal Article |
| Year |
1994 |
Publication |
Applied Physics Letters |
Abbreviated Journal |
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| Volume |
64 |
Issue |
5 |
Pages |
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 |
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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. |
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Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium |
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00036951 (ISSN) |
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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 |
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BT @ osquigui @ |
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390 |
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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 |
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Journal Article |
| Year |
1994 |
Publication |
Applied Physics Letters |
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| Volume |
65 |
Issue |
6 |
Pages |
770-772 |
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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. |
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Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium |
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00036951 (ISSN) |
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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 |
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BT @ osquigui @ |
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391 |
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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 |
1369-1370 |
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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. |
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Laboratorium voor Vaste-Stoffysika en Magnetisme, Katholieke Universiteit Leuven Celestijnenlaan 200D, B-3001 Leuven, Belgium |
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09214534 (ISSN) |
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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 |
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BT @ osquigui @ |
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392 |
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van Dalen, A.J.J.; Griessen, R.; Libbrecht, S.; Osquiguil, E.; Bruynseraede, Y. |
| Title |
Observation of quantum creep in oxygen deficient YBa2Cu3O7-? at fields up to 7 T |
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Journal Article |
| Year |
1994 |
Publication |
Physica C: Superconductivity and its applications |
Abbreviated Journal |
Phys C Supercond Appl |
| Volume |
235-240 |
Issue |
PART 5 |
Pages |
2959-2960 |
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Superconducting current densities js and dynamic relaxation rates Q ? d ln js/d ln (dBe/dt) in an oxygen deficient YBa2Cu3O7-? epitaxial film were measured as a function of temperature (1.5K < T < Tirr) in magnetic fields up to 7 T by means of high sensitivity capacitance torquemeters. Below 5 K, the relaxation rate remains high and does not extrapolate to Q = 0 at T = 0K. This is associated to the quantum tunneling of vortices through the energy barrier separating two adjacent vortex configurations. In the case of ohmic dissipation the quantum creep rate is proportional to the normal state resistivity ?{variant}n(0) at T = 0 K. In order to check this theoretical prediction we measured Q as a function of the oxygen content of the sample. The quantum creep rate increases systematically with increasing ?{variant}n(0). However, Q remains finite even when ?{variant}n = 0. |
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09214534 (ISSN) |
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Export Date: 17 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: van Dalen, A.J.J.; Faculty of Physics and Astronomy; Free University 1081 HV Amsterdam, Netherlands |
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BT @ osquigui @ |
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393 |
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Libbrecht, S.; Osquiguil, E.; Bruynseraede, Y. |
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Influence of field inhomogeneity on the magnetization of YBCO films |
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Journal Article |
| Year |
1994 |
Publication |
Physica C: Superconductivity and its applications |
Abbreviated Journal |
Phys C Supercond Appl |
| Volume |
225 |
Issue |
3-4 |
Pages |
337-345 |
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Magnetization; Superconducting films; SQUID magnetometers; Superconducting ceramics; YBCO superconductors; High temperature superconductors |
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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. |
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Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium |
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09214534 (ISSN) |
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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 |
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BT @ osquigui @ |
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394 |
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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 |
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1994 |
Publication |
Physica C: Superconductivity and its applications |
Abbreviated Journal |
Phys C Supercond Appl |
| Volume |
222 |
Issue |
3-4 |
Pages |
341-348 |
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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 |
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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. |
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Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium |
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09214534 (ISSN) |
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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 |
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BT @ osquigui @ |
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395 |
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Wuyts, B.; Osquiguil, E.; Maenhoudt, M.; Libbrecht, S.; Gao, Z.X.; Bruynseraede, Y. |
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Influence of the oxygen content on the normal-state Hall angle in YBa2Cu3Oxn films |
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Journal Article |
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1993 |
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Physical Review B |
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47 |
Issue |
9 |
Pages |
5512-5515 |
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We report on measurements of in-plane resistivity ?ab(T) and Hall coefficient RH(T) in c-axis-oriented oxygen-deficient YBa2Cu3Oxn thin films. Independent of the changes induced in RH(T) and ?ab(T) by the oxygen depletion, a quadratic temperature dependence is observed for the Hall angle ?H. The slope of cot?H versus T2 decreases as the oxygen content xn is reduced and saturates in the Tc(xn)=60 K plateau region. The results are discussed in the framework of the two-dimensional Luttinger liquid theory as proposed by Anderson. |
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Laboratorium Voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium |
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01631829 (ISSN) |
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Cited By (since 1996): 27; Export Date: 17 April 2009; Source: Scopus; doi: 10.1103/PhysRevB.47.5512; Language of Original Document: English; Correspondence Address: Wuyts, B.; Laboratorium Voor Vaste Stof-Fysika en Magnetisme; Katholieke Universiteit Leuven; Celestijnenlaan 200D B-3001 Leuven, Belgium |
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BT @ osquigui @ |
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398 |
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Osquiguil, E.; Gao, Z.X.; Maenhoudt, M.; Wuyts, B.; Libbrecht, S.; Bruynseraede, Y. |
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YBa2Cu3Ox: A natural multilayer system with tunable anisotropy |
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Journal Article |
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1993 |
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Journal of Physics: Condensed Matter |
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5 |
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33 A |
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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. |
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Lab. voor Vaste Stof-Fysika en Magnetisme, Katholieke Univ. Leuven, Belgium |
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09538984 (ISSN) |
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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 |
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