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Bruynseraede, Y., E. Osquiguil, M. Maenhoudt, B. Wuyts, G. Nieva, J. Guimpel, D. Lederman, and I. K. Schuller. "New Properties of Oxygen Depleted YBa2Cu3Ox Films." Proceedings of the II International Conference on Macroscopic Quantum Phenomena ICMQP-2 (1992): 253.
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Bruynseraede, Y., E. Osquiguil, M. Maenhoudt, B. Wuyts, G. Nieva, J. Guimpel, D. Lederman, and I. K. Schuller. "Enhancement of Superconductivity by Photoexcitation." The Vortex State (NATO Science Series C: Mathematical and Physical Sciences) 438 (1994): 303–312.
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Libbrecht, S., A. J. J. van Dalen, B. Wuyts, M. Maenhoudt, Z. X. Gao, E. Osquiguil, R. Griessen, and Y. Bruynseraede. "Magnetic properties of oxygen deficient Yba2Cu3Ox thin films." Physica C: Superconductivity and its applications 235-240, no. PART 5 (1994): 2889–2890.
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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Osquiguil, E., Z. X. Gao, M. Maenhoudt, B. Wuyts, S. Libbrecht, and Y. Bruynseraede. "YBa2Cu3Ox: A natural multilayer system with tunable anisotropy." Journal of Physics: Condensed Matter 5, no. 33 A (1993).
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.
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Nieva, G., E. Osquiguil, J. Guimpel, M. Maenhoudt, B. Wuyts, Y. Bruynseraede, M. B. Maple, and I. K. Schuller. "Photoinduced enhancement of superconductivity." Applied Physics Letters 60, no. 17 (1992): 2159–2161.
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.
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Wuyts, B., E. Osquiguil, M. Maenhoudt, S. Libbrecht, Z. X. Gao, and Y. Bruynseraede. "Relation between the Hall angle slope and the carrier density in oxygen-depleted YBa2Cu3Ox films." Physica C: Superconductivity and its applications 222, no. 3-4 (1994): 341–348.
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.
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Wuyts, B., Z. X. Gao, S. Libbrecht, M. Maenhoudt, E. Osquiguil, and Y. Bruynseraede. "Growth of particle-free YBa2Cu3O7 films by off-axis sputtering." Physica C: Superconductivity and its applications 203, no. 3-4 (1992): 235–239.
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.
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Osquiguil, E., M. Maenhoudt, B. Wuyts, and Y. Bruynseraede. "Controlled preparation of oxygen deficient YBa2Cu 3Ox films." Applied Physics Letters 60, no. 13 (1992): 1627–1629.
Abstract: We describe a simple method based on the oxygen pressure-temperature phase diagram to prepare oxygen deficient YBa2Cu3Ox thin films. Systematic critical temperature and x-ray diffraction experiments clearly show that films with different oxygen contents (6.6?x?7) are obtained in a controlled, reproducible, and reversible way.
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Vanacken, J., S. Libbrecht, M. Maenhoudt, C. Van Haesendonck, E. Osquiguil, and Y. Bruynseraede. "The magnetic moment relaxation in oxygen-deficient YBa2Cu3Ox." Physica C: Superconductivity and its applications 197, no. 1-2 (1992): 9–14.
Abstract: The magnetic moment relaxation in polycrystalline YBa2Cu3Oxmaterial has been studied using zero-field-cooled measurements. The temperature dependence of the relaxation rate shows a field-dependent maximum. When the oxygen content is reduced, the maximum shifts towards lower temperatures. This shift is directly related to a decrease of the intragrain critical current density in the oxygen-deficient material, inducing a decrease of the field H* for complete flux penetration. The characteristic activation energies for depinning in the oxygen-deficient material are below 20 meV.
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Martin, J. I., B. Wuyts, M. Maenhoudt, E. Osquiguil, J. L. Vicent, V. V. Moshchalkov, and Y. Bruynseraede. "Sign reversal of the flux flow Hall effect in oxygen deficient YBa2Cu3Ox films." Physica C: Superconductivity and its applications 235-240, no. PART 2 (1994): 1451–1452.
Abstract: The Hall effect of high temperature superconductors has been reported to slow in some cases a striking sign reversal near Tc, the origin of which is not yet fully understood. We report on measurements of the Hall effect in the mixed state of oxygen deficient YBa2Cu3Ox thin films, for 7?
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