Electron-phonon coupling superconductivity and tunable topological state in carbon-rich selenide monolayers

作     者：Panlong Kong Xiaotao Zhang Jingjing Wang Wenhui Tian Yuxiang Ni Bai Sun Hongyan Wang Hui Wang Yuan Ping Feng Yuanzheng Chen 

作者机构：School of Physical Science and Technology Southwest Jiaotong University Chengdu 610031 China College of Computer and Information Engineering Hubei Normal University Huangshi 435002 China Frontier Institute of Science and Technology (FIST) Xi'an Jiaotong University Xi'an Shaanxi 710049 China Department of Physics and Centre for Advanced Two-Dimensional Materials National University of Singapore Singapore 117551 Singapore 

出 版 物：《Physical Review B》 (物理学评论B辑：凝聚态物质与材料物理学)

年 卷 期：2023年第107卷第18期

页      面：184115-184115页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

基　　金：Sichuan Province Science and Technology Support Program, (2021YFG0228, 2022ZYD0024) Sichuan Province Science and Technology Support Program National Natural Science Foundation of China, NSFC, (12164009) National Natural Science Foundation of China, NSFC China Postdoctoral Science Foundation, (2021M690325) China Postdoctoral Science Foundation 

主　　题：Composition Density of states Edge states Electron-phonon coupling Electronic structure First-principles calculations Structural properties Superconductivity van Hove singularity 

摘      要：The coexistence of Dirac cones and Van Hove singularities (VHSs), as the notable feature on prominent electronic band structure in recently hot-topic Lieb lattice and twisted graphene superlattice materials, has recently drawn tremendous attention since it offers an ideal platform for realizing correlation-driven electronic states (e.g., superconductivity and topological state). Here, we have identified two two-dimensional (2D) crystals, namely C4Se and C5Se, which exhibit the coexistence of Dirac cones and VHSs. Based on ab initio calculations and the Bardeen-Cooper-Schrieffer theory, we investigated the electron-phonon coupling and possible superconductivity in both structures. The results indicate that C4Se possesses intrinsic superconducting states, whereas C5Se exhibits tunable superconductivity when doped. Their superconducting critical temperature (Tc) can reach up to 11.6 and 11.2 K, respectively, surpassing the majority of 2D superconductors. Besides, we uncovered an approximate Dirac cone in C6Se with a small band gap of 0.17 eV. Via the application of a biaxial compressive strain, remarkably, the C6Se can be transformed into a topological insulator. These findings highlight the potential of carbon-rich C-Se 2D crystals as a promising platform for investigating fascinating band structures and physical states, thus advancing our comprehension of 2D crystals.