Enhancement of c-axis vortex correlation by twin boundaries and columnar defects in YBa2Cu3O7−d

E. F. RIGHI; S. A. GRIGERA; D. LOPEZ; G. NIEVA; F. DE LA CRUZ; L. CIVALE; G. PASQUINI; P. LEVY

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

APS

Año: 1997 vol. 55 p. 5663 - 5665

0163-1829

We report on transport measurements using the flux transformer configuration in a twinned single crystal of YBa2Cu3O72 d with columnar defects. The vortex liquid shows velocity correlation along the c axis the direction of the applied magnetic field and the columnar defects at temperatures that correspond to an uncorrelated liquid in unirradiated samples of the same thickness. These results and previous work about the effect of twin boundaries on vortex velocity correlation show that phase coherence in the field direction is not an intrinsic property of vortex liquids but one induced by extended defects.