Comment on "Axion-matter coupling in multiferroics"

TL;DR

This paper critically evaluates the feasibility of using axion-matter coupling in multiferroics for dark matter detection, concluding current materials and technology are insufficient due to thermal noise and small effects.

Contribution

It provides a critical assessment of previous proposals, highlighting limitations and suggesting the need for materials with lower magnetic ordering temperatures.

Findings

The axion-matter coupling effect is too small to detect with current materials.

Thermal noise dominates the proposed detection scheme.

Materials with lower magnetic ordering temperatures are needed for feasible detection.

Abstract

A previous publication [H. S. Roising et al., Phys. Rev. Research 3, 033236 (2021)] involving the current authors pointed out a coupling between dark matter axions and ferroic orders in multiferroics. In this comment we argue that using this coupling for dark matter sensing is likely not feasible for the material class we considered, with present-day technologies and level of materials synthesis. The proposed effect (for QCD axions) is small and is overwhelmed by thermal noise. This finding means that likely materials for the proposed detection scheme would need to be found with significantly lower magnetic ordering temperatures.