Interplay between density and superconducting quantum critical fluctuations

TL;DR

This paper explores how quantum critical density fluctuations influence superconducting fluctuations near a metal-superconductor transition, revealing a potential mechanism for the suppression of superconductivity at the LaAlO3/SrTiO3 interface.

Contribution

It introduces a theoretical framework describing the interplay between density and superconducting quantum critical fluctuations near a phase separation point.

Findings

Density fluctuations become quantum critical at zero temperature.

Superconducting fluctuations acquire a z=3 dynamical critical index.

Superconductivity may vanish due to density-driven quantum criticality at interfaces.

Abstract

We consider the case of a density-driven metal-superconductor transition in the proximity of an electronic phase separation. In particular we investigate the interplay between superconducting fluctuations and density fluctuations, which become quantum critical when the electronic phase separation vanishes at zero temperature into a quantum critical point. In this situation the critical dynamical density fluctuations strongly affect the dynamics of the Cooper pair fluctuations, which acquire a more singular character with a z=3 dynamical critical index. This gives rise to a scenario that possibly rules the disappearance of superconductivity when the electron density is reduced by elecrostatic gating at the LaAlO3/SrTiO3 interface.