不同氧含量Bi_2Sr_2CaCu_2O_(8+δ)单晶电阻率的各向异性

ANISOTROPIC RESISTIVITIES OF SINGLE CRYSTAL Bi 2Sr 2CaCu 2O 8+ δ WITH DIFFERENT OXYGEN CONTENTS

精确测量了在不同氧压下退火的单晶Ｂｉ２Ｓｒ２ＣａＣｕ２Ｏ８＋δ（Ｂｉ２２１２）样品的ＣｕＯ面内和ＣｕＯ面外的电阻率ρｃ（Ｔ）和ρａｂ（Ｔ）．发现ρｃ（Ｔ）和各向异性比（ρｃ（Ｔ）／ρａｂ（Ｔ））随着载流子浓度增加而迅速下降．在过掺杂样品中，高于１２０Ｋ时，ρｃ随温度线性下降，而各向异性比与温度仅有微弱的依赖关系．

Abstract The in plane resistivity ρ ab (T) and the out of plane ρ c(T) have been extensively measured for pure single crystal Bi 2Sr 2CaCu 2O 8+ δ (Bi2212) annealed at different oxygen pressures.The ρ c(T) and anisotropy ( ρ c(T)/ρ ab (T)) decrease rapidly with increasing carrier concentration.It is found that the out of plane resistivity decreases linearly with decreasing temperature down to about 120K for the overdoped sample,its resistivity anisotropy is of weak temperature dependence.The data of ρ c(T) and ρ c(T)/ρ ab (T) are well fitted by the bipolaron theory proposed by Alexandrov and Mott.