摘要
Ising superconductivity,observed in NbSe2 and similar materials,has generated tremendous interest.Recently,attention was called to the possible role that spin fluctuations(SF)play in this phenomenon,in addition to the dominant electron–phonon coupling(EPC);the possibility of a predominantly triplet state was discussed and led to a conjecture of viable singlet–triplet Leggett oscillations.However,these hypotheses have not been put to a quantitative test.In this paper,we report first principle calculations of the EPC and also estimate coupling with SF,including full momentum dependence.We find that:(1)EPC is strongly anisotropic,largely coming from the K-K0 scattering,and therefore excludes triplet symmetry even as an excited state;(2)superconductivity is substantially weakened by SF,but anisotropy remains as above;and,(3)we do find the possibility of a Leggett mode,not in a singlet–triplet but in an s_(++)–s_(±)channel.
基金
The work at GMU(S.D.and I.I.M.)was supported by Office of Naval Research through grant N00014-20-1-2345
H.P.and E.R.M.acknowledge support from the National Science Foundation(NSF)under Grant No.DMR-2035518 and Grant No.OAC-2103991 for method development,superconductivity analysis,and code develop-ment.D.F.A
was supported by the U.S.Department of Energy,Office of Basic Energy Sciences,Division of Materials Sciences and Engineering,under Award No.DE-SC0021971
This work used the Extreme Science and Engineering Discovery Environment(XSEDE)70 which is supported by NSF Award No.ACI-1548562
Specifically,this work used Comet at the San Diego Supercomputer Center through allocation TG-DMR180071.
