New Class of High Frequency Nonlinear Magnetic Oscillations in Epitaxial Garnet Films

We performed magneto-optical investigations of the shape of the magnetization precession trajectory in garnet films at large precession angle. To describe the precession in asymmetric potential well the second order terms of small magnetization deflections are taken into account in the expansion of the thermodynamical potential. It is shown, that zero and second harmonic appear in the magnetization oscillations spectrum. The amplitude of this harmonics are proportional to the square of the exciting field amplitude. The dependence of asymmetric precession degree upon applied field and film parameters is found. The reported effects are like second harmonic generation and light detection effects in nonlinear optics