Discontinuous Onset of the c-axis Vortex Correlation at the Melting Transition in YBa2Cu3O7

D. LÓPEZ; E. F. RIGHI; G. NIEVA; F. DE LA CRUZ; W. K. KWOK; J. A. FENDRICH; G. W. CRABTREE; L. PAULIUS

Conferencia; 10th Anniversary HTS Workshop; 1996

Transport measurements in untwinned YBCO single crystals using a multiterminal contacts configuration have demonstrated that the long vortex correlations in the c direction is discontinuously established at the liquid-solid transition. The stiffness of vortices against current induced cutting becomes nonzero abruptly at the same temperature. These observations mean that in twin free samples there is no evidence of a disentangled vortex liquid.