Linear and nonlinear magneto-optical phenomena in epitaxial films of europium chalcogenides Eu$X$ ($X$ = O, Se, Te)

The studies of magneto-optical effects in epitaxial films of magnetic semiconductors—europium chalcogenides Eu$X$ ($X$ = O, Se, Te) are presented: linear and quadratic magneto-optical Kerr effects, photo-induced Faraday effect, magnetically-induced optical second and third harmonics generation, the inverse Faraday effect, and the phenomenon of optical orientation. A large quadratic magneto-optical Kerr effect was found in EuO and (Eu, Gd)O films. Photo-induced spin polarons with a huge value of the magnetic moment were studied in europium chalcogenides EuTe and EuSe using the optical pump-probe technique. In the same materials, a new type of nonlinear magneto-optical susceptibility, which is responsible for the optical second harmonic generation and associated with the magnetic ordering of the spins of Eu$^{2+}$ ions, is revealed.