低场下Bi系高温相超导体的不可逆线研究

Study on the Irreversible Line of Bi-based High-T_c Phase Superconductors at Low Magnetic Field

摘要: 采用外加直流磁场测量超导样品交流磁化率的方法,通过对外场Ⅱ和起始抗磁转变温度TP的测量,获得了Bi系高温相超导块材、粉末和晶体样品在低场、液氮温区的不可逆线。块材、粉末和品体样品的不可逆线分别为:(1-T_P/T_c)∝H^0.68、(1-T_P/T_c)∝H^0.61、(1-T_P/T_c)∝H^0.40对不可逆线的意义、被测3种样品磁通钉扎强弱和特性及样品微结构的关系等相关问题进行了分析和讨论。

Abstract: The irreversible lines of Bi-based high-T phase superconductor samples in the form of bulk,powder and crystal slices are obtained by measuring a.c.susceptibility of the samples at the applied d.c.magnetic field.The irreversible lines of the bulk,powder and crystal slice samples at a low magnetic field and LN₂ temperature range are (1-T_P/T_c)∝H^0.68、(1-T_P/T_c)∝H^0.61 and (1-T_P/T_c)∝H^0.40 respectively.The significane of the irreversible line,and,the strength and characteristic of the flux pinning for the three kinds of samples are discussed.The retationship hips between these and the microscopic structure of the samples are also aralyzed.