Axion quasiparticles for axion dark matter detection
Schütte-Engel, J, Marsh, DJE, Millar, AJ, Sekine, A, Chadha-Day, F, Hoof, S, Ali, MN, Fong, KC, Hardy, E, Šmejkal, L
Abstract
It has been suggested that certain antiferromagnetic topological insulators\ncontain axion quasiparticles (AQs), and that such materials could be used to detect\naxion dark matter (DM). The AQ is a longitudinal antiferromagnetic spin fluctuation\ncoupled to the electromagnetic Chern-Simons term, which, in the presence of an applied\nmagnetic field, leads to mass mixing between the AQ and the electric field. The electromagnetic boundary conditions and transmission and reflection coefficients are computed.\nA model for including losses into this system is presented, and the resulting linewidth\nis computed. It is shown how transmission spectroscopy can be used to measure the\nresonant frequencies and damping coefficients of the material, and demonstrate conclusively the existence of the AQ. The dispersion relation and boundary conditions permit\nresonant conversion of axion DM into THz photons in a material volume that is independent of the resonant frequency, which is tuneable via an applied magnetic field. A\nparameter study for axion DM detection is performed, computing boost amplitudes and\nbandwidths using realistic material properties including loss. The proposal could allow\nfor detection of axion DM in the mass range between 1 and 10 meV using current and\nnear future technology.