Jamwal Prarena, Ahuja Rajeev, Kumar Rakesh
Department of Physics, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India.
Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala 75120, Sweden.
J Phys Condens Matter. 2025 Jul 2;37(27). doi: 10.1088/1361-648X/ade7e9.
The interplay of superconducting and topological states in two-dimensional (2D) materials has gained intensive attention for exploring novel quantum phenomena and their applications in quantum computing. However, 2D materials exhibiting both superconductivity and topological phases are exceptionally rare. In this context, we investigated 2D CrH(chromium dihydride) in P-6m2 (hexagonal) and P-3m1 (trigonal) symmetries using first-principles calculations. We verified the stability of these phases using phonon dispersion and mechanical stability analyses. Based on ourinvariant calculations, CrHis topologically nontrivial for the P-6m2 symmetry, while it is topologically trivial for the P-3m1 symmetry. Using anisotropic Migdal-Eliashberg equations, we find both phases as single-gap superconductors, with transition temperatures of ∼11 K for the hexagonal phase and ∼8 K for the trigonal phase. The superconducting properties are attributed to electron-phonon coupling between Cr-orbitals and low-energy phonon modes dominated by Cr vibrations. Our findings offer a promising foundation for further exploration of co-existence of topological and superconducting states in monolayer hydrides and their experimental realization.
二维（2D）材料中超导态与拓扑态的相互作用，在探索新型量子现象及其在量子计算中的应用方面受到了广泛关注。然而，同时展现超导性和拓扑相的二维材料极为罕见。在此背景下，我们利用第一性原理计算研究了具有P-6m2（六方）和P-3m1（三角）对称性的二维CrH（二氢化铬）。我们通过声子色散和力学稳定性分析验证了这些相的稳定性。基于我们的不变量计算，CrH对于P-6m2对称性而言是拓扑非平凡的，而对于P-3m1对称性则是拓扑平凡的。使用各向异性的Migdal-Eliashberg方程，我们发现这两个相均为单能隙超导体，六方相的转变温度约为11 K，三角相的转变温度约为8 K。超导特性归因于Cr轨道与以Cr振动为主的低能声子模式之间的电子-声子耦合。我们的研究结果为进一步探索单层氢化物中拓扑态与超导态的共存及其实验实现提供了一个有前景的基础。
