The Migdal effect in solid crystals and the role of non-adiabaticity

TL;DR

This paper demonstrates that the Migdal effect in solid crystals arises solely from non-adiabatic effects, with a matrix element matching previous low energy effective theory results, highlighting the importance of non-adiabaticity.

Contribution

It clarifies the origin of the Migdal effect in crystals by linking it to non-adiabatic effects and confirms the consistency with existing effective theory calculations.

Findings

Migdal effect in crystals is due to non-adiabatic effects.

The derived matrix element matches previous effective theory results.

Highlights the significance of wave function deviations from adiabatic approximation.

Abstract

We systematically apply the Born-Oppenheimer approximation to show that the Migdal effect in a solid crystal is entirely due to non-adiabatic effects, namely the deviation of the wave function from exact factorization of the electronic and nuclear contributions. The matrix element obtained this way matches exactly the result found by means of a previously derived low energy effective theory.