Magneto-optics of type-II superconductors

The magneto-optical activity of superconducting ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$ observed by Karraï et al. is not present in many commonly employed models of vortex dynamics. Here we propose a simple, unifying picture for the frequency-dependent magneto-optic response of type-II superconductors at low temperatures. We bring together Kohn’s theorem, vortex core excitations, and vortex pinning and damping into a simple expression for the conductivity tensor. The theory describes magneto-optical activity observed in infrared transmission measurements of thin films of ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$.