Observation of Surface Superconductivity in a 3D Dirac Material
Observation of Surface Superconductivity in a 3D Dirac Material
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3D 狄拉克材料中表面超导性的观察
DOI：
10.1002/adfm.202208616
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发表时间：
2022
影响因子：
19
通讯作者：
Yi‐Yan Wang
中科院分区：
文献类型：
--
作者：
Qi Liu;Peng‐Jie Guo;Xiao‐Yu Yue;Zhe‐Kai Yi;Qing‐Xin Dong;Hui Liang;Dan‐Dan Wu;Yan Sun;Qiu‐Ju Li;Wen‐Liang Zhu;Tian‐Long Xia;Xue‐Feng Sun;Yi‐Yan Wang
由于超导电性对于探索奇异的量子现象或发展超导电子学具有重要意义，所以当它遇到维度约束或拓扑结构时，它变得更加有趣。本文报道了BaMg_2Bi2单晶中自然形成的表面超导态和三维拓扑Dirac态共存的现象。由第一性原理计算得到的电子结构表明，BaMg2Bi2是一种理想的Dirac材料，其Dirac点非常接近费米能级，没有其他能带跨越费米能级。在电阻率测量中，常压下可以观察到4.77−−5.17K的超导电性。各向异性的上临界场和随角度变化的磁阻揭示了超导电性的二维特性，表明超导电性发生在样品的表面，在体态下不存在。这一研究不仅为研究超导电性与拓扑Dirac态之间的相互作用提供了一个合适的平台，而且表明了镁铋系材料可能是探索新型超导体的一种很有前途的体系。
Superconductivity becomes more interesting when it encounters dimensional constraint or topology because it is of importance for exploring exotic quantum phenomena or developing superconducting electronics. Here, the coexistence of naturally formed surface superconducting state and 3D topological Dirac state in single crystals of BaMg2Bi2is reported. The electronic structure obtained from the first‐principles calculations demonstrates that BaMg2Bi2is an ideal Dirac material, in which the Dirac point is very close to the Fermi level and no other energy band crosses the Fermi level. Superconductivity up to 4.77−−5.17 K can be observed under ambient pressure in the measurements of resistivity. The anisotropic upper critical field and angle dependent magnetoresistance reveals the 2D characteristic of superconductivity, indicating that superconductivity occurs on the surface of the sample and is absent in the bulk state. The study not only provides BaMg2Bi2as a suitable platform to study the interplay between superconductivity and topological Dirac state but also indicates that MgBi‐based materials may be a promising system for exploring new superconductors.