高温超导体的“尖峰效应”

文章介绍了高温超导体中的“尖峰效应”，即临界电流随着磁场增加反而升高的反常现象。在很多超导体中，包括常规超导体和高温超导体，都存在着“尖峰效应”，这说明“尖峰效应”反映了磁通晶格的普遍性质，“尖峰效应”中钉扎以及温度密切相关，并且由于钉扎和势激活效应的相互作用，其表现非常复杂，目前对尖峰效应的主要理论解释是基于尖峰效应对应着从低场下的布拉格玻璃态到高场下的磁通玻璃态的相变，该理论和最近的很多实验结果符合得很好。文章最后对仍然存在析大量问题进行了介绍，例如尖峰附近的历史效应和 稳态以及磁通相图上的临界点。

PEAK EFFECT IN HIGH TEMPERATURE SUPERCONDUCTOR

The phenomenon of the peak effect in high temperature superconductors, which is characterized by a fast increase of critical current with increase of magnetic field, is discussed. The peak effect has been observed in both conventional superconductors and high temperature superconductors, mainfesting this to be a general property of vortex matter. The interaction of pinning and thermal fluctuation plays an important role in the peak effect and makes it even more complex. The main theoretical explanation of this effect is based on the phase transition between Bragg glass and vortex glass, which has been supported by many recent experimental results. Some unresolved problems, such as the history effect and metastable state around the region of the peak effect, and the critical point in the vortex phase diagram are also discussed.