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 pai...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.展开更多
This study demonstrates that magnetron-sputtered NbSe_(2)film can be used as a lubricant for space current-carrying sliding contact,which accommodates both metal-like conductivity and MoS_(2)-like lubricity.Deposition...This study demonstrates that magnetron-sputtered NbSe_(2)film can be used as a lubricant for space current-carrying sliding contact,which accommodates both metal-like conductivity and MoS_(2)-like lubricity.Deposition at low pressure and low energy is performed to avoid the generation of the interference phase of NbSe_(3).The composition,microstructure,and properties of the NbSe_(2)films are further tailored by controlling the sputtering current.At an appropriate current,the film changed from amorphous to crystalline,maintained a dense structure,and exhibited excellent comprehensive properties.Compared to the currently available electrical contact lubricating materials,the NbSe_(2)film exhibits a significant advantage under the combined vacuum and current-carrying conditions.The friction coefficient decreases from 0.25 to 0.02,the wear life increases more than seven times,and the electric noise reduces approximately 50%.展开更多
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)+5 种基金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。
文摘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.
基金The authors are grateful to the National Natural Science Foundation of China(Grant No.51775537)Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.Y202084)for financial support.
文摘This study demonstrates that magnetron-sputtered NbSe_(2)film can be used as a lubricant for space current-carrying sliding contact,which accommodates both metal-like conductivity and MoS_(2)-like lubricity.Deposition at low pressure and low energy is performed to avoid the generation of the interference phase of NbSe_(3).The composition,microstructure,and properties of the NbSe_(2)films are further tailored by controlling the sputtering current.At an appropriate current,the film changed from amorphous to crystalline,maintained a dense structure,and exhibited excellent comprehensive properties.Compared to the currently available electrical contact lubricating materials,the NbSe_(2)film exhibits a significant advantage under the combined vacuum and current-carrying conditions.The friction coefficient decreases from 0.25 to 0.02,the wear life increases more than seven times,and the electric noise reduces approximately 50%.
