Detection of sub-MeV Dark Matter with Three-Dimensional Dirac Materials

TL;DR

This paper explores using three-dimensional Dirac materials as innovative targets for detecting sub-MeV dark matter, leveraging their unique electronic properties to improve sensitivity to low-mass dark matter particles.

Contribution

It introduces a formalism for dark matter detection in Dirac materials and demonstrates their potential to detect keV to MeV mass dark matter more effectively than existing methods.

Findings

Dirac materials can detect dark matter scattering in the keV to MeV range.

They provide superior sensitivity to light bosonic dark matter absorption.

Dark photon detection benefits from the in-medium effects in Dirac materials.

Abstract

We propose the use of three-dimensional Dirac materials as targets for direct detection of sub-MeV dark matter. Dirac materials are characterized by a linear dispersion for low-energy electronic excitations, with a small band gap of O(meV) if lattice symmetries are broken. Dark matter at the keV scale carrying kinetic energy as small as a few meV can scatter and excite an electron across the gap. Alternatively, bosonic dark matter as light as a few meV can be absorbed by the electrons in the target. We develop the formalism for dark matter scattering and absorption in Dirac materials and calculate the experimental reach of these target materials. We find that Dirac materials can play a crucial role in detecting dark matter in the keV to MeV mass range that scatters with electrons via a kinetically mixed dark photon, as the dark photon does not develop an in-medium effective mass. The same target materials provide excellent sensitivity to absorption of light bosonic dark matter in the meV to hundreds of meV mass range, superior to all other existing proposals when the dark matter is a kinetically mixed dark photon.