高温超导体低温、高压下的物理性质的研究

 在3~20 GPa压力范围内，测量了含氧量较低的YBa₂Cu₃O_7-δ（δ=0.46）单晶压力增强效应（dT_c/dp=4.9KGPa^-1）；YBa₂Cu₃O₇（T_c0=90 K）单晶在压力下临界电流密度随压力变化；外磁场H=30 kO_e时，T_c与磁场、压力关系；压力达16.5 GPa下，Bi₂Sr₂CaCu₂O_x单晶T_c(p)关系（dT_c/dp=-0.4 KGPa^-1）。发现Y系高温超导体的温度压力导数dT_c/dp与T_c0中间呈dT_c/dp=b-mT_c0线性关系（b、m为常数）。结合压力下Y系超导体结构相变和含氧量对T_c影响，分析这类超导体T_c有很强的正压力效应的原因。把实验结果同几种超导电性微观理论模型进行了分析和比较。

PROPERTIES OF HIGH-Tc SUPERCONDUCTORS UNDER HIGH PRESSURE AND LOW TEMPERATURE

The pressure dependence of the superconducting transition temperatures T_c, of single crystal YBa₂Cu₃O_7-δ (δ=0.46) and Bi₂Sr₂CaCu₂O_x were measured. The pressure derivatives, dT_c/dp, were determined to be 4.9 KGPa^-1 for YBa₂Cu₃O_7-δ (δ=0.46) and -0.4 KGPa^-1 for Bi₂Sr₂CaCu₂O_x. Such a large change in T_c with increasing pressure was never observed before in Y₁₂₃ specimens with a T_c0 of about 47 K at p=0. The dT_c/dp is a function of T_c0, which can be written as dT_c/dp=b-mT_c0 (b and m are constants). The results are explained via the pressure induced structure phase transition in Y₁₂₃, the influence of the oxygen vacancies on the T_c.