【摘要】 借助于电子顺磁共振技术(EPR)研究了高 T_c 超导体 BiPbSrCaCuO 的低场微波吸收信号随温度和磁场的变化规律,结果表明这种低场信号和高 T_c 超导电性密切相关.从样品的低场信号谱上得到一个与温度有关的临界场 H_c(T),在外加磁场低于 H_c 时,其信号与磁场无关,而当外加磁场高于 H_c 时,其信号随磁场增加而明显变弱,在 H_c(T)曲线上观察到两个台阶的存在,这两个台阶分别对应于温度～100K 和～104K,同时我们注意到在样品的低场信号强度 S(T)曲线上存在非单调特性,这些现象或许反映了磁通在样品中穿透的行为,进一步地我们认为通过上述的低场信号的研究有可能为高 T_c 氧化物超导体提供另一种可能的研究手段.更多还原

【Abstract】 The change of microwave absorption signal at lower field with tempeiature and the applied field in BiPbSrCaCuO high-Tc superconductor was studied by the observation of electron paramagnetic resonance (EPR).The result shows that this signal has close relation with high Tc superconductivity.A critical field Hc relative to temperature is obtained from the spectra.The signal is independent of the applied field H when H is lower than Hc,while it weakens obviously with increasing H when H higher than Hc.Two steps,corresponding to temperatures-100K and-104K respectively,is setn in its Hc(T) curve.We also note non-monotonous characteristic in its signal intensity S(T) curves.There phenomena may reflect the behavior of the magnetic flux penetration in the simple.Further more,it is proposed that the detection of this signal may provide another possible means to study high-Tc oxide superconductors.更多还原