Enhancement of Ising superconductivity in monolayer NbSe_(2) via surface fluorination  

作　　者：WU JiZheng SHI WuJun WANG Chong DUAN WenHui XU Yong SI Chen 

机构地区：[1]School of Materials Science and Engineering,Beihang University,Beijing 100191,China [2]Center for Transformative Science,ShanghaiTech University,Shanghai 201210,China [3]Shanghai High Repetition Rate XFEL and Extreme Light Facility(SHINE),ShanghaiTech University,Shanghai 201210,China [4]State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics,Tsinghua University,Beijing 100084,China [5]Frontier Science Center for Quantum Information,Beijing 100084,China

出　　处：《Science China(Technological Sciences)》2024年第7期2099-2106,共8页中国科学（技术科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 12274013, 11874079);and the Independent Research Project of Medical Engineering Laboratory of Chinese PLA General Hospital (Grant No. 2022SYSZZKY10);Wujun Shi was supported by the Science and Technology Commission of Shanghai Municipality (STCSM) (Grant No. 22ZR1441800);Yong Xu and Wenhui Duan were supported by the Basic Science Center Project of NSFC (Grant No. 52388201);the National Natural Science Foundation of China (Grant No. 12334003);the National Science Fund for Distinguished Young Scholars (Grant No. 12025405);the Beijing Advanced Innovation Center for Future Chip (ICFC);the Beijing Advanced Innovation Center for Materials Genome Engineering。

摘　　要：Recently discovered Ising superconductors have garnered considerable interest due to their anomalously large in-plane upper critical fields(B_(c2)). However, the requisite strong spin-orbital coupling in the Ising pairing mechanism generally renders these superconductors heavy-element dominant with notably low superconducting transition temperatures(Tc). Here, based on the Migdal-Eliashberg theory and the mean-field Bogoliubov-de Gennes Hamiltonian, we demonstrate a significant enhancement of Ising superconductivity in monolayer NbSe_(2) through surface fluorination, as evidenced by concomitant improvements in Tcand Bc_(2). This enhancement arises from three predominant factors. Firstly, fluorine atoms symmetrically and stably adhere to both sides of the monolayer NbSe_(2), thereby maintaining the out-of-plane mirror symmetry and locking carrier spins out-of-plane.Secondly, fluorination suppresses the charge density wave in monolayer NbSe_(2) and induces a van Hove singularity in the vicinity of the Fermi level, leading to a marked increase in the number of carriers and, consequently, strengthening the electron-phonon coupling(EPC). Lastly, the appearance of fluorine-related, low-frequency phonon modes further augments the EPC. Our findings suggest a promising avenue to elevate Tcin two-dimensional Ising superconductors without compromising their Ising pairing.

关 键 词：Ising superconductivity surface functionalization upper critical field NbSe_(2) first-principles calculations 

分 类 号：TB34[一般工业技术—材料科学与工程]