Magnetic Field-induced Effects in Photon Scattering and Absorption by Crystals

Abstract

Electrons respond in a variety of ways to a steady magnetic field, and bulk material properties include helicon waves, Faraday rotation of the plane of polarization of photons and many other magneto-optic effects. Information about electrons at an atomic level of detail is obtained from Bragg diffraction, and diffraction enhanced by an atomic resonance provides information not available by any other technique in the science of materials, e.g., the direct observation of magnetic charge and anapoles. We formulate resonant Bragg diffraction from crystalline materials subject to a steady magnetic field. By way of illustration of our general findings for field-induced effects in diffraction enhanced by E1–E1 and E1–M1 resonances, we calculate unit-cell structure factors for diffraction from multiferroic gallium ferrate and anti-ferromagnetic copper oxide. In addition, we provide expressions for frequency-integrated dichroic signals conjugate to standard magneto-optic effects, such as Faraday rotation.