Bi_2Sr_2CaCu_2O_(8+δ)单晶超导临界温度的各向异性  

ANISOTROPY OF SUPERCONDUCTING CRITICALTEMPERATURE IN Bi_2Sr_2CaCu_2O_(8+δ) SINGLE CRYSTALS

作　　者：冯双久[1] 周海东[1] 李广[1] 时亮[1] 孙学峰[1] 李晓光[1] 

机构地区：[1]中国科学技术大学结构分析开放研究实验室,材料科学与工程系,合肥230026

出　　处：《低温物理学报》2001年第4期275-279,共5页Low Temperature Physical Letters

基　　金：国家重点基础研究专项经费 (NKBRSF G19990 6 46 );国家自然科学基金资助项目

摘　　要：研究了具有不同氧含量的Bi2 Sr2 CaCu2 O8+δ单晶超导临界温度的各向异性 .通过测量沿ab面和c轴的电阻率发现 ,在轻欠掺杂到过掺杂区域 ,单晶沿ab面和c轴的Tc 值是比较接近的 ,但在重欠掺杂区 ,沿ab面的Tc 值比c轴的Tc 明显高 .从平衡态的相位涨落模型可以得到 ,由于涨落效应对c轴的临界电流密度的压制作用比对ab面的要强 ,导致了Tc 的各向异性 .但这种模型无法解释重欠掺杂超导体中ab面和c轴的Tc 如此大的差别 .我们认为重欠掺杂超导体中的相位涨落行为不同于其他掺杂超导体中的行为 ,实验和理论上都值得进一步深入研究 .The anisotropy of superconducting critical temperature in Bi 2Sr 2CaCu 2O 8+ δ single crystals with different oxygen contents is investigated. By measuring the in-plane and out-of-plane resistivity of the crystals, it is found that the in-plane and out-of-plane critical temperature T c show large difference in strongly underdoped superconductors, in contrast to the materials in other doping ranges. From equilibrium phase fluctuations model, one finds that the fluctuation effect can suppress the out-of-plane critical current density more severely than that of the in-plane′s, which results in the anisotropy of T c in cuprates. However, this model can not account for the large difference of T c in strongly underdoped superconductors. We thought that the fluctuation behaviors in strongly underdoped superconductors are different from these of superconductors in other doping ranges, further investigations in theory and experiment are needed to elucidate this problem.

关 键 词：铜氧化物超导体 Bi2Sr2CaCu2O8+δ 单晶 临界温度 各向异性 涨落效应 

分 类 号：O511[理学—低温物理]