Bogoliubov shadow bands in the normal state of superconducting systems with strong pair fluctuations

TL;DR

This paper demonstrates how precursors of superconductivity, specifically overdamped Bogoliubov modes, appear in the normal state of systems with strong pair fluctuations, using a Boson Fermion model and flow equation techniques.

Contribution

It introduces a novel application of flow equations to reveal Bogoliubov shadow bands in the normal state of superconducting systems with strong pairing fluctuations.

Findings

Overdamped Bogoliubov modes emerge above the transition temperature.

Resonant two-particle scattering induces precursors of superconductivity.

Flow equations effectively separate coherent and incoherent spectral contributions.

Abstract

On the basis of a scenario where electron pairing is induced by resonant two-particle scattering (the Boson Fermion model), we show how precursors of the superconducting state - in form of overdamped Bogoliubov modes - emerge in the normal state upon approaching the transition temperature from above. This result is obtained by a renormalization technique based on continuous unitary transformations (the flow equations), projecting out the coherent contributions in the electron spectral function from an incoherent background.