Small anisotropy, weak thermal fluctuations, and high field superconductivity in Co-doped iron pnictide Ba(Fe1-xCox)2As2
Small anisotropy, weak thermal fluctuations, and high field superconductivity in Co-doped iron pnictide Ba(Fe1-xCox)2As2
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DOI：
10.1063/1.3081455
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发表时间：
2009-02-09
影响因子：
4
通讯作者：
Mandrus, D.
中科院分区：
文献类型：
--
作者：
Yamamoto, A.;Jaroszynski, J.;Mandrus, D.
我们对122相铁磷属元素化物Ba（Fe 1-xCox）（2）As-2的单晶进行了高场磁输运和磁化测量。Ba（Fe_（1-x）Co_x）（2）As_（2-）在45 T以下的磁场下几乎不出现电阻转变增宽，这与高温超导体铜酸盐和1111相氧磷族化合物不同。我们报告了平行和垂直于c轴的上临界场H-c2，不可逆场H-irr（c）（T）和一个相当不寻常的对称体积钉扎力曲线F-p（H）的温度依赖性，表明一个强大的钉扎纳米结构。从dH（c2）（ab）/dT=4.9 T/K和dH（c2）（c）/dT=2.5 T/K的斜率推导出的各向异性参数gamma=H-c2（ab）/H-c2（c）从T-c附近的接近2下降到较低温度下的接近1.5，远小于1111磷族元素和高T-c铜酸盐的gamma。
We performed high-field magnetotransport and magnetization measurements on a single crystal of the 122-phase iron pnictide Ba(Fe1-xCox)(2)As-2. Unlike the high-temperature superconductor cuprates and 1111-phase oxypnictides, Ba(Fe1-xCox)(2)As-2 showed practically no broadening of the resistive transitions under magnetic fields up to 45 T. We report the temperature dependencies of the upper critical field H-c2 both parallel and perpendicular to the c-axis, the irreversibility field H-irr(c)(T), and a rather unusual symmetric volume pinning force curve F-p(H) suggestive of a strong pinning nanostructure. The anisotropy parameter gamma=H-c2(ab)/H-c2(c) deduced from the slopes of dH(c2)(ab)/dT=4.9 T/K and dH(c2)(c)/dT=2.5 T/K decreases from similar to 2 near T-c, to similar to 1.5 at lower temperatures, much smaller than gamma for 1111pnictides and high-T-c cuprates.