角分辨比热揭示的FeSe(0.45)Te(0.55)中序参量的各向异性结构。

Anisotropic structure of the order parameter in FeSe(0.45)Te(0.55) revealed by angle-resolved specific heat.

作者信息

Zeng B, Mu G, Luo H Q, Xiang T, Mazin I I, Yang H, Shan L, Ren C, Dai P C, Wen H-H

机构信息

National Laboratory for Superconductivity, Institute of Physics and National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China.

出版信息

Nat Commun. 2010 Nov 16;1:112. doi: 10.1038/ncomms1115.

DOI:10.1038/ncomms1115

PMID:21081910

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC3066551/

Abstract

The central issues for understanding iron (Fe)-based superconductors are the symmetry and structure of the superconducting gap. So far the experimental data and theoretical models have been highly controversial. Some experiments favor two or more constant or nearly constant gaps, others indicate strong anisotropy and yet others suggest gap zeros ('nodes'). A unique method for addressing this issue, and one of very few methods that are bulk and angle resolved, is measuring the electronic-specific heat in a rotating magnetic field. In this study, we present the first such measurement for an Fe-based high-T(c) superconductor. We observed a fourfold oscillation of the specific heat as a function of the in-plane magnetic field direction. Our results are consistent with the expectations for an extended s-wave model, with a significant gap anisotropy on the electron pockets and the gap minima along the ΓM (Fe-Fe bond) direction.

摘要

理解铁基超导体的核心问题是超导能隙的对称性和结构。到目前为止，实验数据和理论模型一直存在很大争议。一些实验支持两个或更多个恒定或近乎恒定的能隙，另一些实验表明存在很强的各向异性，还有一些实验则暗示能隙为零（“节点”）。一种解决这个问题的独特方法，也是为数不多的几种能够进行体材料和角度分辨测量的方法之一，是在旋转磁场中测量电子比热。在本研究中，我们首次对一种铁基高温超导体进行了此类测量。我们观察到比热随面内磁场方向呈四重振荡。我们的结果与扩展s波模型的预期一致，在电子口袋上存在显著的能隙各向异性，且能隙最小值沿ΓM（铁-铁键）方向。