Abstract
We analyze the structure of an superconducting gap in systems with electron-phonon attraction and electron-electron repulsion. Earlier works have found that superconductivity develops despite strong repulsion, but the gap, , necessarily changes sign along the Matsubara axis. We analyze the sign-changing gap function from a topological perspective using the knowledge that a nodal point of is the center of dynamical vortex. We consider two models with different cutoffs for the repulsive interaction and trace the vortex positions along the Matsubara axis and in the upper frequency half plane on changing the relative strength of the attractive and repulsive parts of the interaction. We discuss how the presence of dynamical vortices affects the gap structure along the real frequency axis, detectable in ARPES experiments.
Original language | English (US) |
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Article number | L140501 |
Journal | Physical Review B |
Volume | 104 |
Issue number | 14 |
DOIs | |
State | Published - Oct 1 2021 |
Bibliographical note
Funding Information:Acknowledgments. We thank A. Abanov, I. Mazin, Y. Wu, and S.-S. Zhang for useful discussions. M.H.C. acknowledges financial support from the Carlsberg foundation. The work by A.V.C. was supported by the NSF DMR-1834856.
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