Second Harmonic Generation in Structures with Inhomogeneous Magnetization Distribution

The interaction of laser radiation with magnetic media is a rapidly developing field of research, offering broad possibilities both for observing new effects and for studying and characterizing magnetic materials at micro- and macrolevels. This is especially important in connection with the development of modern technologies, which allow the creation of structures with fundamentally new magnetic and optical properties, whose realization is impossible in natural materials. The review presents the results of research on nonlinear optical effects in ferromagnetic nano- and microstructures, as well as films of different compositions. The unique possibilities of nonlinear optical diagnostics of anisotropic, vortex, and exchange-biased magnetic structures, visualization of the micromagnetic structure of surface layers of iron–garnets are demonstrated. The exceptional effectiveness of these approaches is based both on the high sensitivity of the method of optical second harmonic generations to the magnetic state of nanostructures and interfaces, and on the properties of symmetry of tensors of high-order magnetization-induced susceptibility.