Lopez, D., E. F. Righi, G. Nieva, F. de la Cruz, W. K. Kwok, J. A. Fendrich, G. W. Crabtree, and L. Paulius. "Amplification of the c-axis vortex correlation by twin-boundary pinning at the vortex liquid-solid phase transition." PHYSICAL REVIEW B 53 (1996): R8895.
Abstract: Transport measurements using the dc flux transformer configuration together with c-axis resistance data in clean and twinned YBa2Cu3O7-δ single crystals show that vortices are localized by the twin-boundary potential. The results support the existence of a divergent tilt modulus [D. R. Nelson and V. M. Vinokur, Phys. Rev. B 48, 13 060 (1993)] in a liquid that freezes into a Bose glass
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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., E. A. Jagla, E. F. Righi, E. Osquiguil, G. Nieva, E. Morré, F. de la Cruz, and C. A. Balseiro. "Dynamic softening of vortex lines in YBa2Cu3O7−δ single crystals." Physica C: Superconductivity 260, no. 3-4 (1996): 211–216.
Abstract: Transport measurements in the mixed state of oxygen-deficient YBa2Cu3O7−δ single crystals using the flux transformer configuration show that the flux liquid changes with increasing anisotropy from strongly correlated to uncorrelated in the field direction. For intermediate coupling, the current inducing loss of vortex correlation has a maximum near the irreversibility temperature. Thus, an effective softening of vortex lines with decreasing temperature is detected. We propose a simple model that accounts for this behavior by including the effects of the pinning potential on the dynamics of vortices.
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de la Cruz, F., D. López, E. F. Righi, and G. Nieva. "Comparative Study of Vortex Correlation in Twinned and Untwinned YBa2Cu3O7 Single Crystals." In Proceedings of the 10th Anniversary Hts Workshop on Physics, Materials and Applications, edited by B. Batlogg, 395. Singapore: World Scientific Publishing Company, 1996.
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López, D., E. F. Righi, G. Nieva, F. de la Cruz, W. K. Kwok, J. A. Fendrich, G. W. Crabtree, and L. Paulius. "Discontinuous Onset of the c-axis Vortex Correlation at the Melting Transition in YBa2Cu3O7." In Proceedings of the 10th Anniversary Hts Workshop on Physics, Materials and Applications, edited by B. Batlogg, 411. Singapore: World Scientific Publishing Company, 1996.
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Righi, E. F., S. A. Grigera, G. Nieva, and F. de la Cruz. "Vortex phase coherence along the c axis in YBa2Cu3O7-d." Superconduvtivity Reviews 2 (1998): 205.
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