Relationship between incommensurability and superconductivity in Peierls distorted charge-density-wave systems

TL;DR

This paper investigates how charge-density wave fluctuations influence superconductivity in Peierls distorted systems, revealing that incommensurability and band structure significantly affect pairing interactions and transition temperatures.

Contribution

It introduces a model analyzing the impact of incommensurability on superconductivity in CDW systems, highlighting the role of vertex renormalization and band substructure.

Findings

Intraband pair scattering scales with the commensurability M.

Interband pair scattering is suppressed with increasing CDW order.

Superconductivity can be enhanced when the chemical potential is inside a subband.

Abstract

We study the pairing potential induced by fluctuations around a charge-density wave (CDW) with scattering vector Q by means of the Froehlich transformation. For general commensurability M, defined as |k+M*Q>=|k>, we find that the intraband pair scattering within the M subbands scales with M whereas the interband pair scattering becomes suppressed with increasing CDW order parameter. As a consequence superconductivity is suppressed when the Fermi energy is located between the subbands as it is usually the case for nesting induced CDW's, but due to the vertex renormalization it can be substantially enhanced when the chemical potential is shifted sufficiently inside one of the subbands. The model can help to understand the experimentally observed dependence of the superconducting transition temperature from the stripe phase incommensurability in the lanthanum cuprates.