| Records |
| 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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| Call Number |
BT @ osquigui @ |
Serial |
396 |
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| Author |
Libbrecht, S.; Osquiguil, E.; Wuyts, B.; Maenhoudt, M.; Gao, Z.X.; Bruynseraede, Y. |
| Title |
Effect of room temperature annealing on the properties of oxygen- deficient YBa2Cu3Ox films |
Type |
Journal Article |
| Year |
1993 |
Publication |
Physica C: Superconductivity and its applications |
Abbreviated Journal |
Phys C Supercond Appl |
| Volume |
206 |
Issue |
1-2 |
Pages |
51-58 |
| Keywords |
Annealing; Ceramic materials; Hall effect; Superconducting films; Yttrium compounds; Critical current density; Oxide superconductors; Yttrium barium copper oxides; High temperature superconductors |
| Abstract |
Annealing at room temperature of quenched oxygen-depleted YBa2Cu3Oxn (6.5?xn<6.8) films, produces a clear increase in the critical temperature Tc and current density Jc, while the normal state resistivity ?{variant}xx and Hall coefficient RH decrease as a function of annealing time, indicating an increase in carrier density. The enhancement of the critical current density Jc is more pronounced at high fields and temperatures due to a shift of the irreversibility line, which scales with the increasing Tc. The observed changes are accompanied by corresponding changes in the crystalline structure, which can be related to oxygen ordering effects. |
| Address |
Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 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: Libbrecht, S.; 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 |
402 |
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| Author |
Dhalle, M.; Boon, W.; Osquiguil, E.; Van Haesendonck, C.; Bruynseraede, Y.; Kwarciak, J.; Van Der Biest, O. |
| Title |
Correlation between critical current and resistivity in YBa2Cu3O7 |
Type |
Journal Article |
| Year |
1991 |
Publication |
Physica C: Superconductivity and its applications |
Abbreviated Journal |
Phys C Supercond Appl |
| Volume |
185-189 |
Issue |
PART 4 |
Pages |
2447-2448 |
| Keywords |
Ceramic Materials; Yttrium Compounds--Electric Conductivity; Critical Currents; Oxide Superconductors; Yttrium Barium Copper Oxides; High Temperature Superconductors |
| Abstract |
Critical current versus temperature measurements were carried out in ceramic YBa2Cu3O7 samples. The samples were all prepared using the same sintering procedure, but starting from powders obtained by different wet and dry methods. All samples showed a linear Jc vs. T behaviour, typical of Josephson weak-link coupling, with a slope that depends on the preparation method. Using the Ambegaokar-Baratoff relation for Jc, the difference in slopes can be attributed to a change in the characteristic value of the junction resistance. This value turns out to be clearly correlated with the resistivity in the normal state. |
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Department of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, de Croylaan 2, 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: Dhalle, M.; 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 @ |
Serial |
410 |
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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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BT @ osquigui @ |
Serial |
413 |
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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 @ |
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397 |
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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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BT @ luzuriag @ |
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483 |
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