Describing Migdal effects in diamond crystal with atom-centered localized Wannier functions

TL;DR

This paper extends the Migdal effect description from isolated atoms to semiconductors using Wannier functions within the tight-binding framework, demonstrated on diamond to evaluate energy spectra and detector sensitivity.

Contribution

It introduces a novel approach to model the Migdal effect in semiconductors with Wannier functions, bridging atomic and solid-state descriptions.

Findings

Method effectively describes Migdal effects in diamond

Calculates energy spectra relevant for dark matter detection

Provides projected sensitivity estimates for diamond detectors

Abstract

Recent studies have theoretically investigated the atomic excitation and ionization induced by the dark matter (DM)-nucleus scattering, and it is found that the suddenly recoiled atom is much more likely to excite or lose its electrons than expected. Such phenomenon is called the "Migdal effect". In this paper, we extend the established strategy to describe the Migdal effect in isolated atoms to the case in semiconductors under the framework of tight-binding (TB) approximation. Since the localized aspects of electrons are respected in form of the Wannier functions (WFs), the extension of the existing Migdal approach for isolated atoms is much more natural, while the extensive nature of electrons in solids is reflected in the hopping integrals. We take diamond target as a concrete proof of principle for the methodology, and calculate relevant energy spectra and projected sensitivity of such diamond detector. It turns out that our method as a preliminary attempt is practically effective.