Nonlinear magnetization-induced terms in garnet film polarization in the second-harmonic generation effect: Theory and experiment

We demonstrate the presence of nonlinear magnetization-induced terms in magnetically ordered crystals in the second-harmonic generation (SHG) effect. The nonlinear terms have been evidenced experimentally in magnetic garnet film and explained theoretically in the frame of a developed phenomenological model. In the model, nonlinear medium polarization up to third order in magnetization is taken into account. We show that all the observed peculiarities of the SHG intensity, measured as a function of the external magnetic field and sample orientation, are in excellent agreement with the predictions of the theoretical model applied to the (111)-oriented garnet film. It is shown that the amplitude of cubic term in magnetization, about one third of the linear term, is required for the explanation of the experiment. It is also shown that the measurements of SHG intensity as a function of both the magnetic field and the sample orientation are necessary to reveal the existence of nonlinear magnetic terms in medium polarization. DOI: 10.1103/PhysRevB.87.024426