We propose the use of several unconventional materials as detectors for dark matter with mass beneath the MeV scale. These include the transition-metal dichalcogenide TiSe2 hosting a low-energy plasmon in the charge-density-wave phase, Sr2RuO4 containing a low-energy acoustic demon mode, and hole-doped diamond with tunable optical and acoustic plasmon frequencies. We perform first-principles density functional theory computations of their loss functions at non-vanishing momenta and establish their reach into light dark matter parameter space. We show that due to intense low-energy plasmon modes -- of different microscopic origin in each -- the reach of detectors based on these materials could surpass existing proposals by several orders of magnitude for both dark matter scattering and absorption on electrons. The anisotropic response of these materials, which enables directional detection, renders them exceptionally strong detector candidates, motivating the design and fabrication of future devices.
@article{arxiv.2507.07164,
title = {Unconventional Materials for Light Dark Matter Detection},
author = {Yonit Hochberg and Dino Novko and Rotem Ovadia and Antonio Politano},
journal= {arXiv preprint arXiv:2507.07164},
year = {2025}
}