电子型超导体Gd掺杂的输运性质研究  

THE STUDY ON THE TRANSPORT PROPERTIES OF ELECTRON-DOPED SUPERCONDUCTORS WITH Gd DOPING

作　　者：杨宏顺[1] 孙成海[1] 成路[1] 王建斌[1] 许祥益[1] 柯少秦[1] 阮可青[1] 

机构地区：[1]中国科学技术大学物理系,安徽合肥230026

出　　处：《低温物理学报》2016年第2期150-155,共6页Low Temperature Physical Letters

摘　　要：在CuO_2平面以外的阳离子格点通过改变Gd含量引入了无序.研究了Nd_(1.85-x)Gd_xCe_(0.15)CuO_4单晶的电阻率ρ、霍耳系数R_H和热电势S.霍耳系数R_H的测量证明这种名义掺杂的改变并没有明显改变载流子的密度.热电势S(T)在120 K以上可用一个掺杂的半经验模型来分析,结果表明存在电子的窄能带和宽能带的共存.无论是电子态密度的带宽和有效电导率的带宽都随着x增加,而局域化的趋势随Gd掺杂增加明显增强.Gd掺杂对超导转变温度T_C的抑制作用很显著.在二维剩余电阻率ρ02D增加超过临界值h/4e^2时没有发生超导-绝缘体转变,观察到的却是超导和局域化的共存效应.量子干涉效应不可以定性地解释Gd掺杂对于电子型超导体的超导转变温度T_c的抑制.Doping Gd into the cation sites outside the CuO2 planes introduce the disorder. The resistivity p（T ）, Hall coefficient RH, and thermopower S（T） are studied for Nd1. 82 T Gd, Ce0.15 CuO4 single crystals. It is confirmed by Ru measurement, such doping nominally does not change the carrier density. The S （T） data above 120 K is analyzed in terms of a semiempirieal model. The results support the coexistence of a broad band and a narrow electron band. Both the bandwidths of the effective conductivity and the density of states and the tendency for localization increase with increasing Gd doping content x. The doping strongly depressed the superconducting transition temperature To. When the two dimensional residual resistivity p02D increase more than the critical value h/4e2 ,the superconducting - insulator transition does not occur, while the co-existence of superconductivity and localization effect is observed. The quantum interference effect can not qualitatively interpret the depress of the superconducting transition temperature Tc.

关 键 词：电子型超导体 热电势 局域化 

分 类 号：O511.3[一般工业技术—材料科学与工程]