电子型超导体Nd_(1.85)Ce_(0.15)CuO_4单晶输运性质研究  

TRANSPORT PROPERTIES OF ELECTRON-DOPED SUPERCONDUCTOR Nd_(1.85)Ce_(0.15)CuO_4 SINGLE CRYSTAL

作　　者：柴一晟[1] 杨宏顺[1] 刘剑[1] 余旻[1] 曹烈兆[1] 

机构地区：[1]中国科学技术大学物理系,结构分析开放实验室,合肥230026

出　　处：《低温物理学报》2003年第4期267-271,共5页Low Temperature Physical Letters

基　　金：国家重点基础研究项目资助的课题 (批准号 :G1 9990 6 4 6 )~~

摘　　要：我们测量了最佳掺杂的Nd1.85Ce0 .15CuO4 单晶的电阻率和ab面以及c方向热电势 .ρ T曲线在高温下表现为非常好的直线 ,超导转变比较尖锐Tc,mid=2 0 .6K ,说明我们的样品品质很好 .低温下的电阻率拟合结果表明频率大约 1 0 0K的软声子模与载流子有强烈相互作用 ,这是极化子模型有力的证据 .对于热电势结果 ,令人惊奇的是 ,无论数值还是曲线形状 ,包括低温曳引峰的位置 ,c方向的热电势Sc 与ab面内的热电势Sab非常接近 .这可能是某种共同的机制导致的结果 .比较Nd1.85Ce0 .15CuO4 和Sm1.85Ce0 .15CuO4 的热电势曲线可以发现 ,二者的数值和曲线形状基本相同 ,而与La1.85Sr0 .15CuO4 差异较大 ,这进一步说明了顶点氧在这些体系中的作用 .The temperature dependence of resistivity in ab plane and thermopower S in ab plane and c axis for Nd-{1.85}Ce-{0.15}CuO single crystal were measured. A fine linear temperature dependent of resistivity was observed in high temperature region. The sharp transition temperature of single crystal T-{c ,mid} is 20.6K, which shows the high quality of the crystal. The fitting result of low temperature resistivity implies a strong interaction between charge carriers and a soft acoustic mode with frequency about 100K, indicating the valid of polaron model. Concerning the thermopower, surprisingly, the temperature dependence of thermopower in ab plane and c axis are very close, not only in values、shapes, but also in the temperature of phonon drags. These might be the results of same mechanism. Comparing the results of thermopower of Nd-{1.85}Ce-{0.15}CuO-4 and Sm-{1.85}Ce-{0.15}CuO-4, they share the almost same value and shape and are quite different from La-{1.85}Sr-{0.15}CuO-4, indicating the impact of the apical oxygen in electron doped system.

关 键 词：电子型超导体 Nd1.85Ce0.15CuO4单晶 输运性质 铜氧化物超导体 电阻率 极化子模型 热电势 

分 类 号：O513[理学—低温物理]