Quantum phase transition in a clean superconductor with repulsive dynamical interaction

We consider a model of electrons at zero temperature, with a repulsive interaction which is a function of the energy transfer. Such an interaction can arise from the combination of electron–electron repulsion at high energies and the weaker electron–phonon attraction at low energies. As shown in pre...

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Bibliographic Details
Published in:npj quantum materials 2022-04, Vol.7 (1), p.1-8, Article 45
Main Authors: Pimenov, Dimitri, Chubukov, Andrey V.
Format: Article
Language:English
Subjects:
639/766/119/1003
639/766/119/2792
639/766/119/2795
Condensed Matter Physics
Electrons
Energy transfer
Phase transitions
Physics
Physics and Astronomy
Quantum Physics
Stiffness
Structural Materials
Superconductivity
Surfaces and Interfaces
Thin Films
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Summary:We consider a model of electrons at zero temperature, with a repulsive interaction which is a function of the energy transfer. Such an interaction can arise from the combination of electron–electron repulsion at high energies and the weaker electron–phonon attraction at low energies. As shown in previous works, superconductivity can develop despite the overall repulsion due to the energy dependence of the interaction, but the gap Δ( ω ) must change sign at some (imaginary) frequency ω 0 to counteract the repulsion. However, when the constant repulsive part of the interaction is increased, a quantum phase transition towards the normal state occurs. We show that, as the phase transition is approached, Δ and ω 0 must vanish in a correlated way such that 1 / ∣ log [ Δ ( 0 ) ] ∣ ~ ω 0 2 . We discuss the behavior of phase fluctuations near this transition and show that the correlation between Δ(0) and ω 0 locks the phase stiffness to a non-zero value.
ISSN:2397-4648
2397-4648
DOI:10.1038/s41535-022-00457-3