电子型超导体Sm_(1.85)Ce_(0.15)CuO_4单晶的赝能隙行为研究  

Pseudogap in electron-doped superconductor Sm_( 1.85) Ce_(0.15) CuO_4 crystal

作　　者：余旻[1] 杨宏顺[1] 柴一晟[1] 李鹏程[1] 李明德 曹烈兆[1] 

机构地区：[1]中国科学技术大学结构开放实验室,物理系合肥230026

出　　处：《物理学报》2002年第8期1832-1835,共4页Acta Physica Sinica

基　　金：国家重点基础研究项目 (批准号 :19990 64 6)资助的课题~~

摘　　要：测量了在O2 中退火不同时间的Sm1 .85Ce0 .1 5CuO4 单晶样品的热电势S与电阻率 ρ的温度依赖关系 .所有的样品电阻率高温下呈现线性温度依赖行为 .未退火的样品在 14 8K发生超导转变 ,而退火后的样品在低温下发生金属 半导体相变 ,其超导电性消失 ,表明退火引起了载流子浓度下降 ,体系进入欠掺杂态 .随着温度降低 ,所有的样品S T和ρ T曲线在 2 0 0K附近 (T )都发生斜率的改变 ,可以用赝能隙现象解释 .热电势S在低温下出现一个正的曳引峰 ,意味着载流子符号发生改变 。The temperature dependence of thermopower S and resistivity ρ for Sm 1.85 Ce 0.15 CuO 4 crystalline samples annealed in flowing oxygen for different days has been measured.All samples show linear temperature dependence.The original sample transformed into superconductor in 14 8K,while the samples annealed in oxygen lost superconductivity and became semiconductors at low temperatures indicating that annealing causes the decrease of the concentration of carrier and leads the system into under doped satate.With the decrease of temperature,the ρ T and S T curves of all samples exhibited changes of slope,which can be explained with pseudogap.A positive excitation drag contribution for thermopower S near 50K is observed in all samples,indicating the changing of the sign of carriers.

关 键 词：Sm1.85Ce0.15CuO4 单晶 电子型超导体 热电势 赝能隙 电子型铜氧化物 

分 类 号：O511[理学—低温物理]