Superconductivity from energy fluctuations in dilute quantum critical polar metals

Abstract

Superconductivity in low carrier density metals challenges the conventional electron-phonon theory due to the absence of retardation required to overcome Coulomb repulsion. In quantum critical polar metals, the Coulomb repulsion is heavily screened, while the critical transverse optic phonons decouple from the electron charge. In the resulting vacuum, the residual interactions between quasiparticles are carried by energy fluctuations of the polar medium, resembling the gravitational interactions of a dark matter universe. Here we demonstrate that pairing inevitably emerges from "gravitational'' interactions with the energy fluctuations, leading to a dome-like dependence of the superconducting $T_c$ on carrier density. Our estimates show that this mechanism may explain the critical temperatures observed in doped SrTiO${}_3$. We provide predictions for the enhancement of superconductivity near polar quantum criticality in two and three dimensional materials that can be used to test our theory.

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• Recent Advances in Unconventional Ferroelectrics and Multiferroics
• Polaron with Quadratic Electron-phonon Interaction
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• Synergetic ferroelectricity and superconductivity in zero-density Dirac semimetals near quantum criticality
• Spin-Phonon Resonances in Nearly Polar Metals with Spin-Orbit Coupling
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• Anisotropic resistivity and superconducting instability in ferroelectric metals
• Phonon-Induced Collective Modes in Spin-Orbit Coupled Polar Metals
• Beyond being free: glassy dynamics of SrTiO${}_3$-based two-dimensional electron gas
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• Polarons with arbitrary nonlinear electron-phonon interaction
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• Electronic spin susceptibility in metallic strontium titanate
• Spin-dependent anisotropic electron-phonon coupling in KTaO${}_3$
• Unconventional superconductivity from electronic dipole fluctuations
• Phonon-mediated spin transport in quantum paraelectric metals
• Effects of doping on polar order in SrTiO${}_3$ from first-principles modeling