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Grigera, S. A., and Morr. "Bose-glass phase in twinned YBa2Cu3O7-?" Physical Review Letters 81, no. 11 (1998): 2348–2351.
Abstract: Using an extensive scaling analysis of the transport properties in twinned YBa2Cu3O7-? crystals we have experimentally found the predicted change in the universality class of the Bose-glass to liquid transition when the magnetic field is applied at small angles away from the direction of the correlated defects. The new dynamical critical exponent is s? = 1.1
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López, D., H. Safar, P. L. Gammel, D. A. Huse, S. N. Majumdar, L. F. Schneemeyer, D. J. Bishop, G. Nieva, and F. de la Cruz. "Reply to the Comment: Local versus Non-Local Conductivity in YBa2Cu3O7-d." Physical Review Letters 75 (1995): 2447.
Abstract: A Reply to the Comment by Yu. Eltsev and O. Rapp.
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Neerinck, D., K. Temst, M. Baert, E. Osquiguil, C. Van Haesendonck, Y. Bruynseraede, A. Gilabert, and I. K. Schuller. "Transition in the flux lattice of artificially layered superconductors." Physical Review Letters 67, no. 18 (1991): 2577–2580.
Abstract: We report a novel magnetic-field dependence of the critical-current density Jc in artificially grown Ge/Pb superlattices. In these layered structures Jc exhibits an unexpected minimum as a function of perpendicular applied field, unlike any ever observed in other superconductor systems. The systematic evolution of this minimum as a function of layer thicknesses, temperature and pinning strength is related to either flux-lattice decoupling or melting.
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Fullerton, E. E., J. Guimpel, O. Nakamura, and I. K. Schuller. "Structure of high-T_{c} superlattices." Physical Review Letters 69, no. 19 (1992): 2859.
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Gao, Z. X., E. Osquiguil, M. Maenhoudt, B. Wuyts, S. Libbrecht, and Y. Bruynseraede. "3D-2D dimensional crossover in YBa2Cu3O7 films." Physical Review Letters 71, no. 19 (1993): 3210–3213.
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.
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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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López, D., E. F. Righi, G. Nieva, and F. de la Cruz. "Coincidence of Vortex-Lattice Melting and Loss of Vortex Correlation along the c Direction in Untwinned YBa2Cu3O7-δ Single Crystals." Physical Review Letters 76 (1996): 4034.
Abstract: We report on transport measurements using the dc flux transformer configuration in clean and twinned single crystals of YBa2Cu3O7-δ. We show that correlated disorder changes not only the order of the solid-liquid phase transition but also the nature of the vortices in the liquid state. In clean crystals, melting is shown to take place between a solid of vortex lines and a liquid with no correlation in the direction of the magnetic field.
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Pedrazzini, P., H. Wilhelm, D. Jaccard, T. Jarlborg, M. Schmidt, M. Hanfland, L. Akselrud, H. Q. Yuan, U. Schwarz, Yu. Grin et al. "Metallic State in Cubic FeGe Beyond Its Quantum Phase Transition." Physical Review Letters 98 (2007): 047204.
Abstract: We report on results of electrical resistivity and structural investigations on the cubic modification of FeGe under high pressure. The long-wavelength helical order (TC=280K) is suppressed at a critical pressure pc≈19GPa. An anomaly at TX(p) and strong deviations from a Fermi-liquid behavior in a wide pressure range above pc suggest that the suppression of TC disagrees with the standard notion of a quantum critical phase transition. The metallic ground state persisting at high pressure can be described by band-structure calculations if zero-point motion is included. The shortest FeGe interatomic distance display discontinuous changes in the pressure dependence close to the TC(p) phase line.
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Correa, V. F., G. Nieva, and F. de la Cruz. "Vortex softening: Origin of the second peak effect in Bi2Sr2CaCu2O8+delta." PHYSICAL REVIEW LETTERS 87, no. 5 (2001): 057003.
Abstract: Magnetic hysteresis and transverse ac permeability measurements in Bi2Sr2CaCu2O8+delta allow a comparative analysis of the critical current with the elastic response of vortex structures, in equilibrium with their pinning potential, in the field and temperature region where the second peak is detected. This study provides strong evidence that the second peak has its origin in changes of the elastic equilibrium properties of the vortex structures.
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Bridoux, G., G. Nieva, and F. de la Cruz. "Phase-coherence effects in vortex transport entropy." PHYSICAL REVIEW LETTERS 101, no. 11 (2008): 117002.
Abstract: Nernst and electrical resistivity measurements in superconducting YBa2Cu3O7-delta and Bi2Sr2CaCu2O8+delta with and without columnar defects show a distinctive thermodynamics of the respective liquid vortex matter. At a field-dependent high temperature region in the H-T phase diagram, the Nernst signal is independent of structural defects in both materials. At lower temperatures, in YBa2Cu3O7-delta, defects contribute only to the vortex mobility, and the transport entropy is that of a system of vortex lines. The transition to lower temperatures in Bi2Sr2CaCu2O8+delta has a different origin; the maximum in the Nernst signal when decreasing temperature is not associated with transport properties but with the entropy behavior of pancake vortices in the presence of structural defects.
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