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arXiv 2304.02243cond-mat.mtrl-scicond-mat.supr-con
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实现超导正方晶格铋单层

Realizing a Superconducting Square-Lattice Bismuth Monolayer

Eunseok Oh, Kyung-Hwan Jin, Han Woong Yeom

AI总结:

在超导Pb薄膜上异质外延生长了具有C4对称性和条纹状moire结构的近邻诱导超导正方晶格铋单层,DFT预测其费米能级存在Rashba型自旋劈裂Dirac能带,为拓扑超导研究提供了新平台。

摘要:

低维材料中晶体对称性、强自旋-轨道耦合(SOC)与多体相互作用的交织,为发现非常规电子和磁性性质及多功能性提供了肥沃土壤。第15族元素的二维(2D)同素异形体因其结构及在强SOC下对对称性和拓扑的可控性而备受关注。在此,我们报告了在超导Pb薄膜上异质外延生长近邻诱导的超导二维正方晶格铋单层。我们的扫描隧道显微镜清晰地解析了具有C4对称性以及条纹状moire结构的单层铋薄膜正方晶格,并通过密度泛函理论(DFT)计算揭示了其原子结构。DFT计算预测,在费米能级上存在Rashba型自旋劈裂的Dirac能带,并通过来自Pb衬底的近邻效应变得超导。我们提出该系统在引入磁性掺杂剂/磁场时存在拓扑超导态的可能性。本工作引入了一个兼具2D Dirac能带、强SOC、拓扑超导和moire超结构的有趣材料平台。

英文摘要:

Interplay of crystal symmetry, strong spin$-$orbit coupling (SOC), and many-body interactions in low dimensional materials provides a fertile ground for the discovery of unconventional electronic and magnetic properties and versatile functionalities. Two-dimensional (2D) allotropes of group 15 elements are appealing due to their structures and controllability over symmetries and topology under strong SOC. Here, we report the heteroepitaxial growth of a proximity-induced superconducting 2D square-lattice bismuth monolayer on superconducting Pb films. The square lattice of monolayer bismuth films in a $C_4$ symmetry together with a stripey moiré structure is clearly resolved by our scanning tunneling microscopy and its atomic structure is revealed by density functional theory (DFT) calculations. A Rashba-type spin-split Dirac band is predicted by DFT calculations to exist at the Fermi level and becomes superconducting through the proximity effect from the Pb substrate. We suggest the possibility of a topological superconducting state in this system with magnetic dopants/field. This work introduces an intriguing material platform with 2D Dirac bands, strong SOC, topological superconductivity, and the moiré superstructure.

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