Records |
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 |
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Volume |
65 |
Issue |
6 |
Pages |
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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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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Call Number  |
BT @ osquigui @ |
Serial |
391 |
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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 |
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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Edition |
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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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Call Number  |
BT @ osquigui @ |
Serial |
392 |
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Author |
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 |
Type |
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 |
Keywords |
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Abstract |
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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Call Number  |
BT @ osquigui @ |
Serial |
393 |
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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 |
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 |
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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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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 |
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 |
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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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no |
Call Number  |
BT @ osquigui @ |
Serial |
395 |
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Author |
Lederman, D.; Osquiguil, E.; Nieva, G.; Guimpel, J.; Hasen, J.; Bruynseraede, Y.; Schuller, I.K. |
Title |
Photoinduced enhancement of superconductivity |
Type |
Journal Article |
Year |
1994 |
Publication |
Journal of Superconductivity |
Abbreviated Journal |
J Supercond |
Volume |
7 |
Issue |
1 |
Pages |
127-130 |
Keywords |
photoconduction; Superconductivity; thin films; Copper oxides; Hall effect; Order disorder transitions; Radiation effects; Superconductivity; X ray analysis; Josephson coupling; Oxide superconductors; Yttrium barium cuprates; High temperature superconductors |
Abstract |
The photoinduced enhancement of superconductivity in RBa2Cu3Ox (R=rare earth or yttrium) and PryR1-yBa2Cu3Ox was explored through temperature-dependent resistivity, Hall coefficient and mobility, and x-ray diffraction measurements. The increases in Tc are enhanced near the metal-insulator transition, although photoinduced changes always exist in oxygendeficient samples. Several explanations, including intergrain Josephson coupling, photoassisted oxygen ordering, and the trapping of photogenerated electrons in oxygen vacancies, are discussed. |
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Kluwer Academic Publishers-Plenum Publishers |
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08961107 (ISSN) |
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Cited By (since 1996): 2; Export Date: 17 April 2009; Source: Scopus; CODEN: JOUSE; doi: 10.1007/BF00730382; Language of Original Document: English; Correspondence Address: Lederman, D.; Physics Department; University of California; San Diego La Jolla, 92093-0319, California, United States |
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no |
Call Number  |
BT @ osquigui @ |
Serial |
397 |
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Author |
Wuyts, B.; Osquiguil, E.; Maenhoudt, M.; Libbrecht, S.; Gao, Z.X.; Bruynseraede, Y. |
Title |
Influence of the oxygen content on the normal-state Hall angle in YBa2Cu3Oxn films |
Type |
Journal Article |
Year |
1993 |
Publication |
Physical Review B |
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Volume |
47 |
Issue |
9 |
Pages |
5512-5515 |
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Abstract |
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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no |
Call Number  |
BT @ osquigui @ |
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398 |
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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 |
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Journal Article |
Year |
1993 |
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Journal of Physics: Condensed Matter |
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Volume |
5 |
Issue |
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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no |
Call Number  |
BT @ osquigui @ |
Serial |
399 |
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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 |
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Volume |
71 |
Issue |
19 |
Pages |
3210-3213 |
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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 |
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00319007 (ISSN) |
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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 |
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Call Number  |
BT @ osquigui @ |
Serial |
400 |
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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 |
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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09258388 (ISSN) |
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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 |
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BT @ osquigui @ |
Serial |
401 |
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