Electromagnetic excitation and dynamical response of ferromagnetic superconductors

Electromagnetic excitation modes in ferromagnetic superconductors are studied theoretically as the coupled modes of photon, electric current and magnetic moments, and their dispersion relations are obtained. With the use of these modes, the reflection coefficient is calculated for the electromagnetic wave incident on the surface of a semi-infinite crystal of ferromagnetic superconductor. It is shown that the reflection coefficient decreases rapidly in the neighborhood of the critical temperature where a spontaneous surface magnetization occurs. An anomaly in the surface impedance is also predicted.