La_(2-x)Ba_xCuO_4单晶反常的正常态输运性质研究  

ANORMALOUS NORMAL STATE TRANSPORT PROPERTIES OF La_(2-x)Ba_xCuO_4 SINGLE CRYSTALS

作　　者：李鹏程[1] 杨宏顺[1] 李志权[1] 柴一晟[1] 余旻[1] 章良[1] 周玉琴[2] 陈兆甲[2] 曹烈兆[1] 

机构地区：[1]中国科学技术大学,物理系,结构分析中心,合肥230026 [2]中科院低温技术实验中心,北京100080

出　　处：《低温物理学报》2001年第2期108-114,共7页Low Temperature Physical Letters

基　　金：国家重点基础研究发展项目

摘　　要：测量了La2 -xBaxCuO4 系列单晶样品的电阻率和热电势 ,我们发现 ,当x =0 .12 5(x =1/ 8)时 ,La2 -xBaxCuO4 的载流子是所有样品中局域化最强的 ,但数据分析结果显示 ,它又是弱局域化行为 .文中我们讨论了Tc 的被压制的原因 ,得出这可能与低温下LTO到LTT的结构相变 ,空穴与自旋的静态条纹有序有关 .热电势结果观察不到任何声子曳引的痕迹 ,表明在LBCO体系中电声子的相互作用很弱 .The in-plane electrical resistivity and thermoelectric power have been measured for the single crystals of La\-\{2-x\}Ba\-xCuO\-4 around x=0.125. The room temperature resistivity and thermopower present the maximum values at x=0.125, indicating the carrier concentration is the minimum and the carriers are most strongly localized at x=0.125. The observed semiconductor-like behavior can be well described by the weak-localized quasi-two-dimensional (2D) state. The steep rise in electric resistivity with the x=0.125 sample below 70K is attributed to the formation of static stripe-order of holes and spins which is pinned by the LTT structure, as discovered in La 1.48 Nd 0.4 Sr 0.12 CuO 4. The temperature dependence of electric resistivity below 70K still be well described by the formula of ρ∝lnT. A definite change of slope of thermopower is observed at the LTO-LTT structural phase transition temperature. The origin of the 1/8 anomaly is discussed in the text.

关 键 词：超导体 La2-xBaxCuO4单晶 反常现象 正态常输运性质 低温载流子 局域化 

分 类 号：O513[理学—低温物理] O782[理学—物理]