Vortex matter phase transitions under tilted fields in pristine and Pb-substituted Bi 2Sr 2CaCu 2O 8+ y

Abstract

Vortex matter phase transitions in Bi 2Sr 2CaCu 2O 8+ y (BSCCO) under fields tilted from the c-axis is studied by using Hall probes. Vortex lattice melting ( H m (θ)) and peak effect ( H p (θ)) are found to follow a novel angular scaling; transition fields linearly depends on the in-plane component of the field. The novel scaling is valid in the vortex solid phase up to doping-level-dependent angle, θ*. New anomalies in the magnetization hysteresis curve, H* p and H* cp , appear only at large tilting angles. Above θ*, the angular dependence of H p , H* p , and H* cp changes drastically, suggesting the presence of vortex phase transition at this angle.