高温超导体中的能斯特效应与类涡旋激发

Nernst effect and vortex-like excitations in high temperature superconductors.

简要地介绍了通常金属的能斯特(Nernst)效应,指出 类超导体在混合态的磁通运动产生的能斯特效应远大于正常载流子的贡献.接着介绍了高温超导的La2-xSrxCuO4(LSCO)单晶中涡旋运动产生的大的能斯特信号从Tc一直延续到远高于Tc的温度T0,并报道在Zn掺杂的YBa2Cu3O7-δ(YBCO)外延薄膜中观测到的Tc和T0随Zn质量分数的变化.这些体系的能斯特效应结果充分地显示出高温超导体中在Tc以上可能存在着类磁通涡旋.根据预超导配对的理论图像对实验结果进行了讨论.

After a brief introduction of the Nernst effect in normal metal, it is pointed out that Nernst effect produced by the vortex flow in the mixed state of type Ⅱ superconductors is much larger than that of normal charge carriers. The large Nernst effect due to the vortex flowing in the high-T_c superconducting La_(2-x)Sr_xCuO_4 (LSCO) single crystals remains observable from T_c to a higher temperature T^0. The variation of T_c and T^0 with x in Zn doped YBa_2(Cu_(1-x)Zn_x)_3O_(7-δ) thin films is also reported. The results strongly suggest that there are vortex-like excitations above T_c in high-T_c cuprates. The data are discussed in the frame of preformed Cooper pairing scenario.