摘要
where t=T/T<sub>c</sub>. Yeshurun et al. studied the irreversibility line ofYBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> single crystal, and obtained a relation similar to expression（1）. The authors also obtained a similar relation from Bi<sub>1.7</sub>Pb<sub>0.3</sub>Sr<sub>2</sub>Ca<sub>2</sub>Cu<sub>3</sub>O<sub>y-x</sub>F<sub>x</sub> bulk superconductor, its values of H<sub>0</sub> are different above and below 9550 A/m. Research of Rango et al. on Bi<sub>1.4</sub>Pb<sub>0.6</sub>Sr<sub>2</sub>Ca<sub>2</sub>Cu<sub>3</sub>O<sub>10</sub>
