Zhang Zhongyi, Wu Zhenfei, Fang Chen, Zhang Fu-Chun, Hu Jiangping, Wang Yuxuan, Qin Shengshan
Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
Beijing National Research Center for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China.
Nat Commun. 2024 Sep 12;15(1):7971. doi: 10.1038/s41467-024-52156-1.
We present a new scheme for Majorana modes in systems with nonsymmorphic-symmetry-protected band degeneracy. We reveal that when the gapless fermionic excitations are encoded with conventional superconductivity and magnetism, which can be intrinsic or induced by proximity effect, topological superconductivity and Majorana modes can be obtained. We illustrate this outcome in a system which respects the space group P4/nmm and features a fourfold-degenerate fermionic mode at (π, π) in the Brillouin zone. We show that in the presence of conventional superconductivity, different types of topological superconductivity, i.e., first-order and second-order topological superconductivity, with coexisting fragile Wannier obstruction in the latter case, can be generated in accordance with the different types of magnetic orders; Majorana modes are shown to exist on the boundary, at the corner and in the vortices. To further demonstrate the effectiveness of our approach, another example related to the space group P4/ncc based on this scheme is also provided. Our study offers insights into constructing topological superconductors based on bulk energy bands and conventional superconductivity and helps to find new material candidates and design new platforms for realizing Majorana modes.
我们提出了一种在具有非对称对称保护能带简并的系统中实现马约拉纳模式的新方案。我们发现，当无隙费米子激发由传统超导性和磁性编码时（这可以是本征的或由近邻效应诱导的），可以获得拓扑超导性和马约拉纳模式。我们在一个遵循空间群P4/nmm且在布里渊区的(π, π)处具有四重简并费米子模式的系统中说明了这一结果。我们表明，在存在传统超导性的情况下，根据不同类型的磁序，可以产生不同类型的拓扑超导性，即一阶和二阶拓扑超导性，在后一种情况下存在共存的脆弱万尼尔阻碍；马约拉纳模式被证明存在于边界、角点和涡旋中。为了进一步证明我们方法的有效性，还提供了基于该方案的另一个与空间群P4/ncc相关的例子。我们的研究为基于体能带和传统超导性构建拓扑超导体提供了见解，并有助于寻找新的材料候选物和设计实现马约拉纳模式的新平台。
