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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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Griessen, R., Wen Hai-Hu, A. J. J. Van Dalen, B. Dam, J. Rector, H. G. Schnack, S. Libbrecht, E. Osquiguil, and Y. Bruynseraede. "Evidence for mean free path fluctuation induced pinning in YBa2Cu3O7 and YBa2Cu4O8 films." Physical Review Letters 72, no. 12 (1994): 1910–1913.
Abstract: The critical current jc and the pinning energy Uc have been determined for three types of yttrium-based superconducting films from current js and dynamic relaxation Q=d lnjs/d ln(dB/dt) data by means of the generalized inversion scheme. For B<2 T and T<80 K the temperature dependence of jc and Uc for all films is found to be in excellent agreement with a model of single vortices pinned by randomly distributed weak pinning centers via spatial fluctuations of the charge carrier mean free path. Pinning due to spatial fluctuations of Tc is not observed.
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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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Grigera, S. A., E. Morre, E. Osquiguil, C. Balseiro, G. Nieva, and F. de la Cruz. "Bose-glass phase in twinned YBa2Cu3O7-delta." PHYSICAL REVIEW LETTERS 81, no. 11 (1998): 2348–2351.
Abstract: Using an extensive scaling analysis of the transport properties in twinned YBa2Cu3O7-delta 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 +/- 0.3.
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Hoffmann, A., G. Nieva, J. Guimpel, Y. Bruynseraede, J. Santamaria, D. Lederman, and I. K. Schuller. "Comment on “Photoemission study of YBa2Cu3Oy thin films under light illumination”." PHYSICAL REVIEW LETTERS 97, no. 11 (2006): 119701.
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Jenkins N., Fasano Y., Berthod C., Maggio-Aprile I., Piriou A., Giannini E., Hoogenboom B. W., Hess C., Cren T., and Fischer Ø. "Imaging the essential role of spin-fluctuations in high-Tc superconductivity." Physical Review Letters 103 (2009): 227001–227004.
Abstract: We have used scanning tunneling spectroscopy to investigate short-length electronic correlations in three-layer Bi2Sr2Ca2Cu3O10+δ (Bi-2223). We show that the superconducting gap and the energy Ωdip, defined as the difference between the dip minimum and the gap, are both modulated in space following the lattice superstructure and are locally anticorrelated. Based on fits of our data to a microscopic strong-coupling model, we show that Ωdip is an accurate measure of the collective-mode energy in Bi-2223. We conclude that the collective mode responsible for the dip is a local excitation with a doping dependent energy and is most likely the (π, π) spin resonance.
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Killer, U., E. - W. Scheidt, G. Eickerling, H. Michor, J. Sereni, T. Pruschke, and S. Kehrein. "Unusual Single-Ion Non-Fermi-Liquid Behavior in Ce{1-x}La{x}Ni{9}Ge{4}." Physical Review Letters 93, no. 21 (2004): 216404.
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Kuchler, R., P. Gegenwart, J. Custers, O. Stockert, N. Caroca-Canales, C. Geibel, J. G. Sereni, and F. Steglich. "Quantum criticality in the cubic heavy-fermion system CeIn3-xSnx." Physical Review Letters 96, no. 25 (2006): 256403.
Abstract: We report a comprehensive study of CeIn3-xSnx (0.55 <= x <= 0.8) single crystals close to the antiferromagnetic quantum-critical point (QCP) at x(c)approximate to 0.67 by means of the low-temperature thermal expansion and Gruneisen parameter. This system represents the first example for a cubic heavy fermion in which T-N can be suppressed continuously down to T=0. A characteristic sign change of the Gruneisen parameter between the antiferromagnetic and paramagnetic states indicates the accumulation of entropy close to the QCP. The observed quantum-critical behavior is compatible with the predictions of the itinerant theory for three-dimensional critical spin fluctuations. This has important implications for the role of the dimensionality in heavy-fermion QCPs.
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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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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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