La_2CuO_4掺锌样品的低温电阻率与热导率研究  

A study of thermal conductivity and resistivity 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] 杨东升[1] 章良[1] 王喻宏 李明德[1] 曹烈兆[1] 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3期679-684,共6页Acta Physica Sinica

基　　金：国家重点基础研究项目 (批准号 :G199906 46 )资助的课题~~

摘　　要：对La2 CuO4掺锌样品在不同降温速率下 (330K保温 30min后 ,分别以 6K h和 0 2K s的速率冷却至 4 2K)电阻率 (4 2— 330K)和热导率 (80— 30 0K)随温度的变化关系进行了研究 .实验结果表明 ,在不同降温速率下 ,热导率和电阻率都受到很大影响 .快速降温过程使得 130K以上的热导率减小 ,而热导率最小值出现在 130K ,且与降温速率无关 .而低温下的热导率不受降温速率变化的影响 .样品在高温区 (T高于 12 5K)电阻率随降温速率的增大而增大 ,低温区电阻率的非线性行为可用变程跳跃行为来描述 .所有样品的热导率和电阻率在反铁磁相变温度都没有出现反常 ,这与能带理论框架下预期的结果和Anderson电荷 自旋分离理论发生了矛盾 ,对此进行了讨论 ,并用极化子理论进行了自洽解释 .We report on a study of the temperature dependence of thermal conductivity and resistivity of Zn-doped La 2CuO 4 with slow cooling and slow warming after quenching. The thermal conductivity above 130K is reduced by quenching. A minimum appears at 130K, which is not sensitive to the cooling rate. Moreover, the low-temperature thermal conductivity is not affected by changing the cooling rate, which is consistent with the fact that the resistivity is also insensitive to the cooling rates at low temperatures. In the low-temperature region (T<125 K), the resistivity in the nonmetallic regime does not change with the change of cooling rate and it can be described with the variable range hopping law. We also found that both thermal conductivity and resistivity do not show any trace of anomaly at T N for both the parameters. This suggests that the dominate contribution in transport properties is not from the energy band, and this is in opposition to Anderson's theory of spin-charge separation. These contradictions can be explained by the polaron theory.

关 键 词：LA2CUO4 热导率 低温电阻率 锌掺杂 高温氧化物超导体 超导铜氧化合物 

分 类 号：O482[理学—固体物理]