Superconductivity from Orbital-Selective Electron-Phonon Coupling in $A{\mathrm{V}}_3{\mathrm{Sb}}_5$

Abstract

Recent experiments have shown that the phase diagrams of the kagome superconductors $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ are strongly impacted by changes in the $c$-axis lattice parameter. Here, we show that $c$-axis deformations impact primarily the Sb apical bonds and thus the overlap between their $p_z$ orbitals. Changes in the latter, in turn, substantially affect low-energy electronic states with significant Sb character, most notably the central electron pocket and the van Hove singularities located above the Fermi level. Based on the orbital-selective character of $c$-axis strain, we argue that these electronic states experience a non-negligible attractive electron-phonon pairing interaction mediated by fluctuations in the apical Sb bonds. We thus propose a multi-band model for superconductivity in $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ that includes both the Sb pocket and the V-derived van Hove singularities. Upon comparing the theoretical phase diagram with the experimentally observed vanishing of the $T_c$ dome across a Lifshitz transition of the Sb pocket, we propose that either an $s^{+-}$ or an $s^{++}$ state is realized in $A{\mathrm{V}}_3{\mathrm{Sb}}_5$.

7+5 pages, 2+4 figures. Accepted in Phys. Rev. B

References in corpus (11)

• Ironing out the details of unconventional superconductivity
• Absence of local moments in the kagome metal KV3Sb5 as determined by muon spin spectroscopy
• Nodeless electron pairing in CsV${}_3$Sb${}_5$-derived kagome superconductors
• Loop currents in $A$V${}_3$Sb${}_5$ kagome metals: multipolar and toroidal magnetic orders
• Temperature-driven reorganization of electronic order in CsV${}_3$Sb${}_5$
• Revealing the competition between charge-density wave and superconductivity in CsV${}_3$Sb${}_5$ through uniaxial strain
• Competing orders at higher-order Van Hove points
• Charge density wave order in kagome metal AV${}_3$Sb${}_5$ (A= Cs, Rb, K)
• Nodeless superconductivity in kagome metal CsV${}_3$Sb${}_5$ with and without time reversal symmetry breaking
• Valley magnetism, nematicity, and density wave orders in twisted bilayer graphene
• Superconductivity from repulsive interactions on the kagome lattice

Cited by in corpus (15)

• Unconventional superconductivity protected from disorder on the kagome lattice
• Origin and stability of the charge density wave in ScV${}_6$Sn${}_6$
• Unconventional gapping behavior in a kagome superconductor
• Pressure-dependent Electronic Superlattice in the Kagome-Superconductor CsV${}_3$Sb${}_5$
• Kagome metals
• Existence of Hebel-Slichter peak in unconventional kagome superconductors
• Conventional Superconductivity in the Doped Kagome Superconductor Cs(V0.86Ta0.14)3Sb5 from Vortex Lattice Studies
• Kagome KMn${}_3$Sb${}_5$ metal: Magnetism, lattice dynamics, and anomalous Hall conductivity
• Interplay of superconductivity and charge-density-wave order in kagome materials
• Inversion and Tunability of Van Hove Singularities in $A$V${}_3$Sb${}_5$ ($A$ = K, Rb, and Cs) kagome metals
• Calculated Unconventional Superconductivity via Charge Fluctuations in Kagome Metal CsV3Sb5
• Loop-current order through the kagome looking glass
• Magnetic field-induced momentum-dependent symmetry breaking in a kagome superconductor
• Beyond kagome: $p$-bands in kagome metals
• Strain-Tuned Nodal Superconductivity in the Charge-Ordered Kagome Metal CsV${}_3$Sb${}_5$