Axion electrodynamics in a topologically trivial antiferromagnet (opens in new tab)

Axion electrodynamics, originally proposed by Frank Wilczek in the context of high energy physics, can manifest in condensed matter systems as an isotropic linear magnetoelectric (ME) response. Yet, experimental realization of a continuous and purely monopolar ME response has remained elusive. Here, we demonstrate such a response by transforming the topologically trivial antiferromagnet chromia into an isotropic ME medium. Using low-frequency AC ME susceptometry, supported by Monte Carlo simu...