Enhancement of Ising superconductivity in monolayer NbSe2 via surface fluorination

WU JiZheng ¹SHI WuJun ²WANG Chong ³DUAN WenHui ⁴XU Yong ⁴SI Chen¹

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作者信息

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

Recently discovered Ising superconductors have garnered considerable interest due to their anomalously large in-plane upper critical fields(Bc2).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 NbSe2 through surface fluorination,as evidenced by concomitant improvements in Tc and Bc2.This enhancement arises from three predominant factors.Firstly,fluorine atoms symmetrically and stably adhere to both sides of the monolayer NbSe2,thereby maintaining the out-of-plane mirror symmetry and locking carrier spins out-of-plane.Secondly,fluorination suppresses the charge density wave in monolayer NbSe2 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 Tc in two-dimensional Ising superconductors without compromising their Ising pairing.

Key words

Ising superconductivity/surface functionalization/upper critical field/NbSe2/first-principles calculations

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基金项目

National Natural Science Foundation of China(Grant Nos.12274013)

National Natural Science Foundation of China(11874079)

Independent Research Project of Medical Engineering Laboratory of Chinese PLA General Hospital(2022SYSZZKY10)

Science and Technology Commission of Shanghai Municipality(STCSM)(22ZR1441800)

Basic science Center Project of NSFC(52388201)

National Natural Science Foundation of China(12334003)

National Science Fund for Distinguished Young Scholars(12025405)

Beijing Advanced Innovation Center for Future Chip(ICFC)()

Beijing Advanced Innovation Center for Materials Genome Engineering()

出版年

2024

中国科学:技术科学(英文版)

中国科学院

中国科学:技术科学(英文版)

CSTPCDEI

影响因子：1.056

ISSN：1674-7321

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