Chiral phonons as dark matter detectors

TL;DR

This paper proposes using chiral phonons in metal-organic frameworks as highly sensitive dark matter detectors, capable of detecting single phonons with low energy thresholds, vastly surpassing current detection limits.

Contribution

It introduces a novel detection method utilizing chiral phonons in MOFs, with specific calculations demonstrating their potential for dark matter detection.

Findings

MOFs can host highly chiral acoustic phonons with magnetic moments.

Detection of single chiral phonons could lower dark matter detection thresholds by over ten orders of magnitude.

The proposed method offers directional sensitivity and low background contamination.

Abstract

We propose a method for detecting single chiral phonons that will enable their use as dark-matter detectors. We suggest metal--organic frameworks (MOFs) as detector materials, as their flexibility yields low-energy chiral phonons with measurable magnetic moments, and their anisotropy leads to directional sensitivity, which mitigates background contamination. To demonstrate our proposal, we calculate the phononic structure of the MOF InF$_3$($4,4'$-bipyridine), and show that it has highly chiral acoustic phonons. Detection of such chiral phonons via their magnetic moments would dramatically lower the excitation energy threshold for dark matter detection to the energy of a single phonon. We show that single phonon detection in a MOF would extend detector reach ten or more orders of magnitude below current limits, enabling exploration of a multitude of as-yet-unprobed dark matter candidates.