论文标题
在三维狄拉克材料中观察表面超导性
Observation of surface superconductivity in a three-dimensional Dirac material
论文作者
论文摘要
当遇到尺寸约束或拓扑时，超导性变得更加有趣，因为它对于探索异国情调的量子现象或发展超导电子非常重要。在这里，我们报告了自然形成的表面超导状态和三维拓扑状态的共存，该状态在BAMG $ _2 $ bi $ _2 $的单晶中。从第一原理计算获得的电子结构表明，BAMG $ _2 $ bi $ _2 $是理想的狄拉克材料，其中Dirac点非常接近Fermi级别，没有其他能量频段可以交叉Fermi级别。在电阻率的测量中，在环境压力下可以观察到高达4.77 K的超导性。角度依赖的磁路阻塞揭示了超导性的二维特征，表明超导性发生在样品的表面上，并且在批量状态下不存在。我们的研究不仅提供BAMG $ _2 $ bi $ _2 $作为研究超导性和拓扑迪拉克状态之间相互作用的合适平台，而且还表明基于MGBI的材料可能是探索新超导体的有希望的系统。
Superconductivity becomes more interesting when it encounters dimensional constraint or topology, because it is of importance for exploring exotic quantum phenomena or developing superconducting electronics. Here we report the coexistence of naturally formed surface superconducting state and three-dimensional topological Dirac state in single crystals of BaMg$_2$Bi$_2$. The electronic structure obtained from the first-principles calculations demonstrates that BaMg$_2$Bi$_2$ is 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 K can be observed under ambient pressure in the measurements of resistivity. The angle dependent magnetoresistance reveals the two-dimensional characteristic of superconductivity, indicating that superconductivity occurs on the surface of the sample and is absent in the bulk state. Our study not only provides BaMg$_2$Bi$_2$ as 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.
