Zn掺杂La_2CuO_4热电势和磁化率研究  

Study on the thermopower and magnetic properties of Zn doped La_2CuO_4

作　　者：杨宏顺[1] 李鹏程[1] 柴一晟[1] 余旻[1] 李志权[1] 李明德[1] 曹烈兆[1] 闻海虎[2] 龙云泽[2] 陈兆甲[2] 

机构地区：[1]中国科学技术大学结构分析开放实验室,物理系合肥230026 [2]中国科学院物理研究所,北京100080

出　　处：《物理学报》2002年第9期2155-2160,共6页Acta Physica Sinica

基　　金：国家重点基础研究专项基金 (批准号 :19990 64 6)资助的课题~~

摘　　要：测量了La2 CuO4 掺Zn样品在不同降温速率下 (330K保温 0 5h ,然后分别以 6K h ,0 2K s的速度降到 8K)的直流磁化率和热电势 .实验结果表明 ,反铁磁温度TN 不随降温速率变化而变化 ,其直流磁化率也未受很大影响 .高温热电势弱的温度依赖关系表明为极化子气体的贡献 .热电势在转折温度Tdrop之下的快速降低是由于二维反铁磁涨落的贡献 .热电势在更低温度的拐点TS 与载流子的局域化有关 .降温速率变化时 ,Tdrop和TS 都有明显的变化 .Zn掺杂对Tdrop和TS 没有明显影响 ,但导致了更强的载流子局域化 .We report on a study of the temperature dependence of thermoelectric power and DC susceptibility of Zn doped La2CuO4 throngh slow cooling and slow warming after quenching (6K/h, and 0.2K/s respectively). The antifen-omagnetic (AF) transition temperature T-N does not change with changing cooling rates and the de susceptibility for La2CuO4 is not much affected. The high temperature thermopower is weakly temperature dependent, suggesting the hopping contribution of polarons. The rather rapid linear decrease in the thermopower below T-drop is attributed to the contribution of the two-dimensional AF fluctuations. The spinodal in thermopower at lower temperature is confirmed to be related with the localization of the charge carriers. The T-drop and T-S are obviously changed by changing cooling rates while they are not affected much by Zn doping. However, the Zn doping results in a stronger localization of charge carriers. In this paper, we discuss the physical origins related to above phenomena.

关 键 词：Zn掺杂 LA2CUO4 直流磁化率 热电势 锌掺杂 高温氧化物超导体 铜酸镧 

分 类 号：O511.4[理学—低温物理]