| Records |
| 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 |
Luzuriaga, J.; Andre, M.-O.; Benoit, W. |
| Title |
Frequency and amplitude response of the flux-line lattice to mechanical perturbation in ceramic YBa2Cu3O7 |
Type |
Journal Article |
| Year |
1992 |
Publication |
Physica C: Superconductivity and its applications |
Abbreviated Journal |
Phys C Supercond Appl |
| Volume |
201 |
Issue |
3-4 |
Pages |
257-262 |
| Keywords |
Copper oxides; Crystal lattices; Frequency response; Internal friction; Lattice vibrations; Magnetic fields; Mathematical models; Mechanical properties; Pendulums; Rheology; Thermal effects; Torque; Yttrium compounds; Amplitude response; Ceramic yttrium barium copper oxides; Extended dry friction model; Flux line lattices; Forced pendulum; Frequency independent dissipation peak; Mechanical response; Thermal activation; High temperature superconductors |
| Abstract |
The mechanical response of the flux-line lattice has been measured with a low-frequency forced pendulum in ceramic YBa2Cu3O7. A dissipation peak observed in temperature sweeps is frequency-independent between 1 mHz and 5 Hz. Dissipation depends strongly on applied torque, and for fixed temperatures this dependence is well fitted by a rheological model of extended dry friction. If the model is extended to take account of thermal activation, however, it does not agree with the measured frequency independence, which is hard to explain within simple models of thermal activation. |
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Institut de G |
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09214534 (ISSN) |
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Export Date: 28 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: Luzuriaga, J.; Institut de G |
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no |
| Call Number |
BT @ luzuriag @ |
Serial |
487 |
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| Author |
D'Anna, G.; Andr |
| Title |
Flux-line response in 2H-NbSe2 investigated by means of the vibrating superconductor method |
Type |
Journal Article |
| Year |
1993 |
Publication |
Physica C: Superconductivity and its applications |
Abbreviated Journal |
Phys C Supercond Appl |
| Volume |
218 |
Issue |
1-2 |
Pages |
238-244 |
| Keywords |
Crystals; Defects; Electric currents; Electric losses; Hydrogenation; Niobium compounds; Phase diagrams; Thermal effects; Critical currents; Flux line response; Hydrogenated niobium selenide single crystals; Peak effect; Transverse AC losses; Vibrating superconductor method; Vortex pinning regime; Superconducting materials |
| Abstract |
We measure transverse AC losses in the low- and high-amplitude regime of 2H-NbSe2 single crystals using vibrating superconductor methods. The measurements are sensitive to small deviations of the critical state. The data constitute evidence for a peak effect of the critical current as a function of the temperature in this compound. We construct in the H-T phase diagram the “peak-effect” line which is supposed to mark an abrupt cross-over in the vortex-pinning regime. |
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AT and T Bell Laboratories, Murray Hill, NJ 07974, United States |
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09214534 (ISSN) |
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Cited By (since 1996): 13; Export Date: 28 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: D'Anna, G.; D |
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no |
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BT @ luzuriag @ |
Serial |
521 |
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L |
| Title |
Dynamic softening of vortex lines in YBa2Cu3O7-? single crystals |
Type |
Journal Article |
| Year |
1996 |
Publication |
Physica C: Superconductivity and its Applications |
Abbreviated Journal |
Phys C Supercond Appl |
| Volume |
260 |
Issue |
3-4 |
Pages |
211-216 |
| Keywords |
Crystal defects; Magnetic anisotropy; Magnetic couplings; Mathematical models; Single crystals; Transport properties; Vortex flow; Yttrium compounds; Dynamic softening; Flux transformer configuration; Pinning potential; Transport measurements; Vortex correlation; Vortex line; Yttrium barium cuprates; High temperature superconductors |
| Abstract |
Transport measurements in the mixed state of oxygen-deficient YBa2Cu3O7-? single crystals using the flux transformer configuration show that the flux liquid changes with increasing anisotropy from strongly correlated to uncorrelated in the field direction. For intermediate coupling, the current inducing loss of vortex correlation has a maximum near the irreversibility temperature. Thus, an effective softening of vortex lines with decreasing temperature is detected. We propose a simple model that accounts for this behavior by including the effects of the pinning potential on the dynamics of vortices. |
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Comn. Nac. de Ener. At |
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09214534 (ISSN) |
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Cited By (since 1996): 4; Export Date: 17 April 2009; Source: Scopus; CODEN: PHYCE; Language of Original Document: English; Correspondence Address: Righi, E.F.; Comn. Nac. de Ener. At |
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no |
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BT @ osquigui @ |
Serial |
384 |
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| Author |
Herbsommer, J.A.; Luzuriaga, J.; Cheong, S.-W. |
| Title |
Vortex glass melting in single crystal La1.825 Sr0.075CuO4 |
Type |
Journal Article |
| Year |
1996 |
Publication |
Physica C |
Abbreviated Journal |
Physica C |
| Volume |
258 |
Issue |
1-2 |
Pages |
169-174 |
| Keywords |
Copper compounds; Crystal lattices; Frequency response; Glass; Magnetic field measurement; Magnetic permeability measurement; Melting; Phase diagrams; Single crystals; Temperature; Vortex flow; AC susceptibility; Cuprates; Pinned flux lattice; Oxide superconductors |
| Abstract |
The vortex phase diagram in single crystalline La1.85Sr0.075CuO4 has been studied using an AC-susceptibility technique. A peak in the out-of-phase (x?) component of the susceptibility indicates a transition from a pinned flux lattice (FLL) to an unpinned one. This peak is frequency dependent for all the values of the magnetic field measured (0.01 to 4 T), and this, as well as the general behavior found in the cuprates, has prompted us to interpret our data as evidence for a vortex-glass to liquid transition in the FLL. The activation energies obtained can be fitted to a theory developed by Vinokur et al. Measurements with the magnetic field at an angle with the Cu-O planes may also be understood qualitatively within this framework. |
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AT and T Bell Laboratories, Murray Hill, NJ, United States |
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09214534 (ISSN) |
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Cited By (since 1996): 2; Export Date: 28 April 2009; Source: Scopus; CODEN: PHYCE; doi: 10.1016/0921-4534(95)00812-8; Language of Original Document: English; Correspondence Address: Luzuriaga, J.; Centro At |
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no |
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BT @ luzuriag @ |
Serial |
483 |
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Pedrazzini, P.; Jaccard, D.; Lapertot, G.; Flouquet, J.; Inada, Y.; Kohara, H.; Onuki, Y. |
| Title |
Probing the extended non-Fermi liquid regimes of MnSi and Fe |
Type |
Journal Article |
| Year |
2006 |
Publication |
Physica B – Condensed Matter |
Abbreviated Journal |
Physica B |
| Volume |
378-380 |
Issue |
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Pages |
165-166 |
| Keywords |
electrical resistivity; Fermi liquid; ferromagnetic materials; high-pressure effects; iron; magnetic superconductors; manganese alloys; silicon alloys; strongly correlated electron systems; superconducting transition temperature; superconducting transitions; whiskers; MnSi; Fe |
| Abstract |
Recent studies show that the non-Fermi liquid (NFL) behavior of MnSi and Fe spans over an unexpectedly broad pressure range, between the critical pressure p and around 2p. In order to determine the extension of their NFL regions, we analyze the evolution of the resistivity ρ(T)˜A(p)T at higher pressures. We find that in MnSi the n=32 exponent holds below 4.8GPa≈3p, but it increases above that pressure. At 7.2 GPa we observe the low-temperature Fermi liquid exponent n=2 whereas for T>1.5K, n=53. Our measurements in Fe show that the NFL behavior ρ˜T extends at least up to 30.5 GPa, above the entire superconducting (SC) region. In the studied pressure range, the onset of the SC transition reduces by a factor 10 down to Tconset(30.5GPa)=0.23K, while the A—coefficient diminishes monotonically by around 50%. |
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no |
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BT @ pedrazp @ |
Serial |
469 |
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| Author |
Vanacken, J.; Osquiguil, E.; Bruynseraede, Y. |
| Title |
Irreversibility line and critical currents in oxygen deficient YBa2Cu3Ox ceramics |
Type |
Journal Article |
| Year |
1991 |
Publication |
Physica C: Superconductivity and its applications |
Abbreviated Journal |
Phys C Supercond Appl |
| Volume |
183 |
Issue |
1-3 |
Pages |
163-166 |
| Keywords |
Ceramic Materials; Crystals; Oxygen; Yttrium Compounds; Critical Currents; Oxide Superconductors; Yttrium Barium Copper Oxides; High Temperature Superconductors |
| Abstract |
The influence of oxygen concentration on the irreversibility line and critical current of polycrystalline YBa2Cu3Ox was determined using field and zero-field cooled magnetic measurements and magnetic hysteresis data. Although the field dependence of Tirr(H) is unchanged, the irreversibility line shifts to lower temperatures for decreasing oxygen content and the critical current density is strongly reduced. |
| Address |
Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 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: Vanacken, J.; Laboratorium voor Vaste Stof-Fysika en Magnetisme; Katholieke Universiteit Leuven; Celestijnenlaan 200D 3001 Leuven, Belgium |
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no |
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BT @ osquigui @ |
Serial |
413 |
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Esparza, D.A.; D'Ovidio, C.A.; Guimpel, J.; Osquiguil, E.; Civale, L.; de la Cruz, F. |
| Title |
The granular nature of bulk superconductivity at 40K in La1.8Sr0.2CuO4 |
Type |
Journal Article |
| Year |
1987 |
Publication |
Solid State Communications |
Abbreviated Journal |
Solid State Commun. |
| Volume |
63 |
Issue |
2 |
Pages |
137-140 |
| Keywords |
CERAMIC MATERIALS; GRANULAR MATERIALS; LANTHANUM COMPOUNDS – Electric Conductivity; CRITICAL FIELDS; HIGH TEMPERATURE SUPERCONDUCTOR; MAGNETIC FLUX EXPULSION; TEMPERATURE DEPENDENCE; SUPERCONDUCTING MATERIALS |
| Abstract |
We have measured the electrical resistivity, magnetic flux expulsion and critical fields of the new high temperature superconductor La1.8Sr0.2CuO4 after different heat treatments. Our data show that the complete flux expulsion in these samples is consistent with the presence of shielding currents induced in multiple connected structures. The magnetization measurements indicate that the lowest field where flux penetrates into the sample should not be taken to be the bulk Hcl. It is shown that the absolute value of the electrical resistivity and its temperature dependence are not correlated with the superconducting critical field and temperature. We discuss the behaviour of the superconducting parameters and their relation with the electrical resistivity. |
| Address |
Basic Research Department, Centro At |
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00381098 (ISSN) |
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Export Date: 17 April 2009; Source: Scopus; CODEN: SSCOA; Language of Original Document: English; Correspondence Address: Esparza, D.A.; Applied Research Department; Centro At |
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no |
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BT @ osquigui @ |
Serial |
418 |
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| Author |
Watt |
| Title |
Photoinduced changes in Raman spectra of YBa2Cu3O6.4 films |
Type |
Journal Article |
| Year |
1994 |
Publication |
Journal of Superconductivity |
Abbreviated Journal |
J Supercond |
| Volume |
7 |
Issue |
1 |
Pages |
131-136 |
| Keywords |
Electronic Raman scattering; oxygen ordering; photoinduced superconductivity; two-magnon scattering; Copper oxides; Radiation effects; Raman spectroscopy; Superconducting films; Superconductivity; Oxide superconductors; Photoinduced effects; Yttrium barium cuprates; High temperature superconductors |
| Abstract |
The evolution of Raman spectra with illumination has been studied in YBa2Cu3O6.4 films at temperatures between 5-300 K. Low laser power has always been used to avoid local overheating, which was controlled by measuring the local temperature by the Stokes/anti-Stokes ratio. Three important photoinduced effects have been found: (i) the enhancement of the intensity of the observed phonon modes: (Cu(2) at 141 cm-1, O(2)-O(3) at 338 cm-1, and O(4) at 488 cm-1), which may be related to the ordering of oxygen vacancies, (ii) the increase of the electronic scattering background for low Raman frequencies ?, which is in agreement with the enhancement of the static conductivity ?(??0) after illumination, and (iii) the suppression of the intensity of the two-magnon band, which may be caused by the increase of charge carriers due to photodoping. |
| Address |
Laboratorium voor Vaste Stof-Fysika en Magnetisme, KU Leuven, Leuven, B-3001, Belgium |
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Kluwer Academic Publishers-Plenum Publishers |
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08961107 (ISSN) |
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Cited By (since 1996): 11; Export Date: 17 April 2009; Source: Scopus; CODEN: JOUSE; doi: 10.1007/BF00730383; Language of Original Document: English; Correspondence Address: Watt |
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no |
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BT @ osquigui @ |
Serial |
396 |
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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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Centro At |
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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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BT @ osquigui @ |
Serial |
397 |
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