Tang Meng, Zhang Wenyuan, Yang Guochun, Deng Huiqiu
School of Physics and Electronics, Hunan University, Changsha 410082, China.
State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China.
Phys Chem Chem Phys. 2025 Jan 29;27(5):2766-2771. doi: 10.1039/d4cp04053h.
Two-dimensional (2D) Janus structures with the breaking of out-of-plane mirror symmetry can induce many interesting physical phenomena, and have attracted widespread attention. Herein, we propose a MoPS monolayer with mirror asymmetry, identified by first-principles structural search calculations, which demonstrates high thermodynamic and dynamic stability. Our findings reveal that Mo 4d-orbitals dominate the metallicity, significantly enhancing the density of states near the Fermi level due to Van Hove singularities (VHSs), leading to the existence of phonon-mediated superconductivity. Notably, tensile strain elevates the critical temperature () nearly tenfold, driven by strong coupling between softened acoustic modes of Mo vibrations and a new saddle point VHS at point . These results highlight that the Janus MoPS monolayer serves as a promising candidate for 2D straintronic applications with desirable physical properties.
具有面外镜像对称性破缺的二维（2D）Janus结构可引发许多有趣的物理现象，并已引起广泛关注。在此，我们提出了一种具有镜像不对称性的MoPS单层，通过第一性原理结构搜索计算得以确定，该单层展现出高热力学和动力学稳定性。我们的研究结果表明，Mo 4d轨道主导金属性，由于范霍夫奇点（VHSs）显著提高了费米能级附近的态密度，从而导致声子介导的超导性的存在。值得注意的是，拉伸应变使临界温度（）提高了近十倍，这是由Mo振动的软化声学模式与点处的一个新鞍点VHS之间的强耦合驱动的。这些结果突出表明，Janus MoPS单层作为具有理想物理特性的二维应变电子应用的有前景候选材料。
