Detecting Light Dark Matter with Magnons

Understand

Scattering of light dark matter with sub-eV energy deposition can be detected with collective excitations in condensed matter systems.

• When dark matter has spin-independent couplings to atoms or ions, it has been shown to efficiently excite phonons.
• Here we show that, if dark matter couples to the electron spin, magnon excitations in materials with magnetic dipole order offer a promising detection path.
• We derive general formulae for single magnon excitation rates from dark matter scattering, and demonstrate as a proof of principle the projected reach of a yttrium iron garnet target for several dark matter models with spin-dependent interactions.