Reply to Comment on "Superconductivity at low density near a ferroelectric quantum critical point: doped SrTiO_3"

Abstract

In our paper (Wölfle and Balatsky, Phys. Rev. B 98, 104505 (2018)) we presented a microscopic theory of superconductivity for doped SrTiO${}_3$ by proposing two pairing mechanisms acting simultaneously with relative strength depending on the closeness to the ferroelectric quantum critical point. The first mechanism rests on the dynamically screened Coulomb interaction, and the second assumed a coupling to the soft transverse optical phonon. In their comment Ruhman and Lee point out an error in our estimate of the deformation potential coupling to the soft mode. We agree that this type of coupling cannot explain the gigantic isotope effect observed experimentally, so that a different coupling mechanism needs to be found. As for the first pairing mechanism, Ruhman and Lee maintain the view expressed in their paper (Ruhman and Lee, Phys. Rev. B 94, 224515 (2016)) that the energy range over which the usual longitudinal optical phonon mediated interaction operates is limited by the Fermi energy. We object to this view and in this reply present evidence that the cutoff energy is much larger. In a weak coupling system such as SrTiO${}_3$ the cutoff is given by the energy beyond which quasiparticles cease to be well defined.

arXiv commentReply on a Comment by J. Ruhman and P. Lee. Both the comment and reply to be published in PRB. 4 figures, 5 pages

References in corpus (5)

• Critical doping for the onset of a two-band superconducting ground state in SrTiO${}_{3-\delta }$
• Fermi surface of the most dilute superconductor
• Superconductivity at very low density: the case of strontium titanate
• Superconductivity at low density near a ferroelectric quantum critical point: doped SrTiO
• Comment on "Superconductivity at low density near a ferroelectric quantum critical point: Doped SrTiO3"

Cited by in corpus (7)

• Superconductivity in dilute SrTiO${}_3$: a review
• Anisotropic superconductivity mediated by ferroelectric fluctuations in cubic systems with spin-orbit coupling
• Superconductivity from energy fluctuations in dilute quantum critical polar metals
• Theory of superconductivity mediated by Rashba coupling in incipient ferroelectrics
• Generalized Rashba Electron-Phonon Coupling and Superconductivity in Strontium Titanate
• Multiband Quantum Criticality of Polar Metals
• A large modulation of electron-phonon coupling and an emergent superconducting dome in doped strong ferroelectrics