Zn掺杂La2CuO4热电势和磁化率研究

测量了La2CuO4掺Zn样品在不同降温速率下(330K保温05h,然后分别以6Kh,02Ks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.讨论了上述现象产生的物理图像 关键词： La2CuO4 直流磁化率 热电势

Study on the thermopower and magnetic properties of Zn doped La2CuO4

We report on a study of the temperature dependence of thermoelectric power and DC susceptibility of Zn doped La 2CuO 4 throngh slow cooling and slow warming after quenching (6K/h,and 0.2K/s respectively).The antiferromagnetic (AF) transition temperature T N does not change with changing cooling rates and the dc susceptibility for La 2CuO 4 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.