Large pinning efficiency of orthogonal columnar defects in a weakly anisotropic high-Tc superconductor

Abstract

The pinning efficiency of orthogonal columnar defects has been investigated in weakly anisotropic Tl2/3Bi1/3Sr2CaCu2O7 single crystals [denoted as (Tl, Bi)-1212 hereafter]. Columnar defects were introduced by heavy ion irradiation along two directions tilted by 45° from the c axis. This configuration was compared to a crystal irradiated along the c axis. The whole damaged volume was the same in both samples. Magnetic measurements, performed with H∥c, show that the perpendicularly crossed defects exhibit the highest pinning efficiency in a wide range of fields and temperatures. To analyze this enhancement, which can be related to the splay of crossed defects and/or to the enlargement of the defect section in the (a,b) planes associated with the tilt angle, the (Tl, Bi)-1212 single crystals were compared to a third one, irradiated along one direction only, tilted by 45° from the c axis. Furthermore, these crystals have been compared to a similar set of defect configurations in YBa2Cu3O7, for a tilt angle of 10°, for which a splay effect has already been demonstrated.

Source-reported materials — not catalogue approval

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