VORTEX PHASE TRANSITIONS IN Bi2Sr2CaCu2O8+y IN FIELDS NEARLY PARALLEL AND PERPENDICULAR TO THE CuO2 PLANE

• Published in: Physica. C, Superconductivity Vol. 364-365; pp. 499 - 503
• Main Authors: Tamegai, T, Tokunaga, M, Kishi, M, Koya, S, Kameda, N, Itaka, K
• Format: Journal Article
• Language: English
• Published: 01-11-2001
• ISSN: 0921-4534
• DOI: 10.1016/S0921-4534(01)00833-4

The angular dependence of vortex phase transitions is studied in Bi2Sr2CaCu2O8+y through magnetization measurements using micro-Hall probes, including the two limiting cases, H almost parallel and perpendicular to the CuO2 plane. The crossing lattices ground state is taken over by a homogeneously tilted vortex lattice state at small q. At larger q close to 90 degrees, the linear in-plane field dependence of the vortex phase transition fields breaks down, suggesting the presence of another phase transition. At the transition point, the spacing of pancake vortices becomes nearly equal to the spacing of Josephson vortices along the plane, suggesting a matching effect as a possible origin for this transition. Several other anomalies in the hysteresis curve are also found. Authors discuss possible origins of these anomalies. 12 refs.