Decca, R. S., H. D. Drew, E. Osquiguil, B. Maiorov, and J. Guimpel. "Anomalous proximity effect in underdoped YBa2Cu3O6+x Josephson junctions." Physical Review Letters 85, no. 17 (2000): 3708–3711.
Abstract: Experiments were carried out to probe the underdoped insulating material by the Josephson effect. Junctions were fabricated by exploiting the capability of locally photodoping insulating RBa2Cu3O6+x (R = rare earth) material. The existence of an anomalously large proximity effect was confirmed. The critical current of the junctions was consisted with the conventional Josephson relationship.
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Dhalle, M., W. Boon, E. Osquiguil, C. Van Haesendonck, Y. Bruynseraede, J. Kwarciak, and O. Van Der Biest. "Correlation between critical current and resistivity in YBa2Cu3O7." Physica C: Superconductivity and its applications 185-189, no. PART 4 (1991): 2447–2448.
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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Gonzalez Sutter, J., L. Neñer, H. Navarro, G. Leyva, S. Fusil, K. Bouzehouane, N. Haberkorn, and M. Sirena. "Oxygen influence in the magnetic and the transport properties of ferroelectric/ferromagnetic heterostructures." Thin Solid Films 639 (2017): 42–46.
Abstract: Oxygen vacancies in oxides nanostructures are the origin of many intriguing phenomena. We have studied the influence of the oxygen pressure in the tunneling properties of a ferroelectric barrier, Ba0.25Sr0.75TiO3 (BSTO), grown over a ferromagnetic electrode. A phenomenological model description was used to obtain critical information about the structure and electrical properties of ultra-thin BSTO layers using conductive atomic force microscopy. The BSTO layers present good insulation properties. Reducing the oxygen content increases the conductivity of the samples. The tunneling of the current carriers is probably the main conduction mechanism for samples with higher barrier thicknesses.
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Herbsommer, J. A., J. Luzuriaga, L. Civale, G. Nieva, G. Pasquini, H. Lanza, and P. Levy. "Angular variation of pinning near the irreversibility temperature in single crystal Y Ba2Cu3O7-? with splayed columnar defects." Physica C 304, no. 1-2 (1998): 112–118.
Abstract: We have studied vortex pinning through ac susceptibility measurements in single crystals of YBCO with columnar defects (CDs). The CDs have 0, 10 and 20 splay angle and average direction 108 off the c-axis. By studying the angular variation we can compensate for the anisotropy and effects of twins, etc. Using a simple expression we can obtain the angular spread when the field direction is outside the splay angle. An increase of pinning when the field direction is inside
the angle defined by the CDs can be attributed to vortex entanglement due to the splay and the suppression of the sliding of double kinks.
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Lederman, D., E. Osquiguil, G. Nieva, J. Guimpel, J. Hasen, Y. Bruynseraede, and I. K. Schuller. "Photoinduced enhancement of superconductivity." Journal of Superconductivity 7, no. 1 (1994): 127–130.
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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Libbrecht, S., E. Osquiguil, B. Wuyts, M. Maenhoudt, Z. X. Gao, and Y. Bruynseraede. "Effect of room temperature annealing on the properties of oxygen- deficient YBa2Cu3Ox films." Physica C: Superconductivity and its applications 206, no. 1-2 (1993): 51–58.
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.
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Luzuriaga, J., M. - O. Andre, and W. Benoit. "Frequency and amplitude response of the flux-line lattice to mechanical perturbation in ceramic YBa2Cu3O7." Physica C: Superconductivity and its applications 201, no. 3-4 (1992): 257–262.
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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Maiorov, B., and E. Osquiguil. "Bose-glass-like phases in oriented-twin YBa2Cu3O7-? crystals." Journal of Low Temperature Physics 135, no. 1-2 (2004): 131–134.
Abstract: We experimentally study the dynamical response of the superconducting vortex system near the solid-liquid transition by applying forces parallel and perpendicular to a planar random defect array. Our results show that for magnetic fields above a certain critical field Hcr'? 4 T the solid glassy vortex phase in YBa2Cu3O7-? crystals with oriented twin planes does not correspond to the so-called Bose-glass phase.
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Maiorov, B., A. V. Silhanek, F. De la Cruz, E. Osquiguil, A. Rydh, and Rapp. "Comment on “strong vortex liquid correlation from multiterminal measurements on untwinned YBa2Cu3O7-? single crystals” [2] (multiple letters)." Physical Review Letters 88, no. 13 (2002).
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Nakamura, O., I. Chan, J. Guimpel, and I. Schuller. "New buffer layer for high?temperature superconducting ceramics on sapphire: LaBa2Cu3Oy/Ag bilayers." Applied Physics Letters 59, no. 10 (1991): 1245.
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