Effect of thermomagnetic history of field-cooled magnetization on the irreversibility line in conventional and high-T_c superconductors

Abstract

We report the thermomagnetic history of field-cooled magnetization in conventional hard type-II superconductor (Nb) and in high-T_c superconductor (single crystal of Bi₂Sr₂CaCu₂O_8+y). Among various procedures to locate the irreversibility line, the one generally used is the merger of zero-field-cooled magnetization (M_ZFC) and field-cooled magnetization (M_FC). The thermomagnetic history of M_FC provides the merger of M_XFC and M_FC at two points (one while cooling down, T^c_r(H), and other while warming up, T^w_r(H)) at the same field.