Systematic reduction of magnetization by an ac transverse field and of the anomalous magnetization peak in a N_2-annealed Tl_2Ba_2CuO_6 single crystal

摘要

Measurements of magnetization of N_2-annealed Tl_2Ba_2CuO_6 were carried out by using a micro-Hall sensor while applying a low-ac transverse magnetic field H_(ac) along the ab plane in addition to a dc magnetic field along the c axis. A systematic reduction of dc magnetization was observed, and further, an anomalous second magnetization peak evolved with increasing H_(ac. We explained the observed reduction of magnetization due to a dc electric field generated by an ac transverse field, which leads to the decay of the magnetization and then interpreted the development of the second peak at finite H_(ac) due to the destruction of the vortex lattice by strong point pinning and the subsequent optimal redistribution of two-dimensional vortices to the pinning centers.