RESEARCH ON MAGNETIZATION AND ABNORMALY OF PIN-POTENTIAL IN HIGH-TEMPERATURE OXIDE SUPERCONDUCTORS

磁通蠕动的势垒高度随着温度T的增加而增加，尽管钉扎电势预计会随着T的增加而降低。Welch通过非线性势垒U（J）定性地解释了这种异常，其中分析所围绕的电流J在高温下降低，因此非线性导致高温下的高钉扎势垒能量。为了证实这种机制，U（J）关系的J范围很广。通过将在较高温度T_0 + Δ T下磁化的超导体冷却到工作温度T_0（高温磁化：HTM），实现了与长时间蠕变后的状态等效的低磁化电流J状态。用高温超导法和霍尔电压测量相结合的方法，给出了YBaCuO超导体在宽J范围内的磁弛豫曲线，并根据蠕变方程对这些蠕变曲线进行了详细的分析。用HTM方法扩大了观测窗口，讨论了电流相关钉扎势的本质，模拟了磁通蠕动，并与高温磁化后的磁弛豫进行了比较.从高温变形后的短期观测中，通过平滑连接高温变形后的各蠕变曲线，得到了相当于几个月蠕变特性的偏移蠕变曲线。模拟的特性与热变形后的抑制蠕变曲线和偏移蠕变曲线进行了比较.由偏移蠕变曲线估算的潜深U_0表明，潜深U_0随温度的降低而增大。

Barrier height for the flux creep increases with the temperature T, although the pinning potential is expected to decrease with increasing T.This anomaly was explained qualitatively by Welch by means of nonlinear potential barrier U(J) where the current J around which the analysis is centered decreases at high T and accordingly the nonlinearity leads to high pinning barrier energy at high T.To confirm this mechanism, U(J) relation of a wide range of J is required. By cooling a superconductor magnetized at higher temperature T_0 + DELTAT to an operating temperature T_0(High-Temperature Magnetization : HTM), low magnetization current J states equivalent to those after long-time creep are realized. The combination of the HTM method and the HaIl voltage measurement attached to YBaCuO superconductor gives the magnetic relaxation curve in a wide range of J.These creep curves are analyzed in details with the simulation based on the creep equation. The observation-window is enlarged by HTM method and the nature of the current dependent pinning potentials is discussed.Simulation of the flux creep is performed and compared with the magnetic relaxation after hightemperature magnetization.1. From short-time observations after HTM, offset creep curves equivalent to several months creep characteristics are obtained by smoothly connecting each creep curve after HTM.2. Simulated characteristics are favorably compared with both the suppressed creep curves after HTM and the offset creep curves.3. The potential depth U_0 estimated from the offset creep curves shows that U_0 increases as the temperature reduces.