Evidence for line nodes in the energy gap of the overdoped Ba(Fe1−xCox)2As2from low-temperature specific heat measurements
Evidence for line nodes in the energy gap of the overdoped Ba(Fe1−xCox)2As2from low-temperature specific heat measurements
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来自低温比热测量的过掺杂 Ba(Fe1−xCox)2As2 能隙中线节点的证据
DOI：
10.1103/physrevb.84.054505
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发表时间：
2011
影响因子：
3.7
通讯作者：
K. Tanigaki
中科院分区：
文献类型：
--
作者：
G. Mu;Jun Tang;Y. Tanabe;Jingtao Xu;S. Heguri;K. Tanigaki
研究了Ba(Fe $_{1-x}$ Co $_{x}$) $_2$ As $_2$单晶在不同磁场下的低温比热。对于过掺杂的样品，我们发现数据中明显存在$T^2$项的证据，而在欠掺杂和最佳掺杂的样品中都没有，这表明在过掺杂样品的能隙中存在线节点。此外，过掺杂样品的场致电子比热系数$\Delta\gamma(H)$比欠掺杂和最佳掺杂样品的场致电子比热系数随场的增加更快，这为我们的论点提供了另一个支持。我们的结果表明，本体系中的超导隙可能具有不同的结构，这在很大程度上取决于掺杂区域。
Low-temperature specific heat (SH) is measured on Ba(Fe$_{1-x}$Co$_{x}$)$_2$As$_2$ single crystals in a wide doping region under different magnetic fields. For the overdoped sample, we find the clear evidence for the presence of $T^2$ term in the data, which is absent both for the underdoped and optimal doped samples, suggesting the presence of line nodes in the energy gap of the overdoped samples. Moreover, the field induced electron specific heat coefficient $\Delta\gamma(H)$ increases more quickly with the field for the overdoped sample than the underdoped and optimal doped ones, giving another support to our arguments. Our results suggest that the superconducting gap(s) in the present system may have different structures strongly depending on the doping regions.