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2015: Magnetic nonlinear-optical properties of multilayered magnetic structures were studied

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Scientists from the Faculty of Physics in collaboration with their colleagues from the Institute of Physics of Microstructures of the Russian Academy of Sciences (Nizhny Novgorod) studied linear and nonlinear magneto-optical properties of multilayered magnetic structures.

Magnetotransport and magneto-optical properties of planar films, composed by alternating layers of ferromagnetic and nonmagnetic materials, are the subject of intensive study during last few decades. Combination of materials with different ferromagnetic properties in one structure allows realization of different types of magnetic arrangement, including antiferromagnetic, which can be characterized by the magnetic toroid moment. Fundamental interest arises, studying the exchange interaction of magnetic layers and features of nonlinear-optical effects as the diagnostic method of structures with inhomogeneous magnetization.

Scientists from the Faculty of Physics (Chair of General Physics and Chair of Quantum Eectronics) along with colleagues from Institute for Physics of Microstructures of the Russian Academy of Sciences (Nizhny Novgorod) studied linear and nonlinear magneto-optical properties of the films CoFe (20 nm)/Al2O3 (2 nm)/СоFe (10 nm)/Ni3Fe (2 nm) deposited on glass substrates. The presence of Ni3Fe provides the different coercive forces of magnetic layers and forming the antiferromagnetic structure for a definite range of applied magnetic field.

The optical second harmonic generation and transversal magnetic nonlinear-optical effect were studied in these multilayer structures. It was revealed that the shape of hysteresis loops strongly depends on the experimental geometry and the polarization of the fundamental beam. It was shown, that taking into account both linear and quadratic in magnetization contributions of the nonlinear polarization is necessary for the explanation of experimental data. It was revealed that exchange interaction of magnetic layers can be easily visualized by means of second harmonic generation technique. A phenomenological description of the observed phenomena was constructed.

The results of this work have been published in the paper: I.A. Kolmychek, V.L. Krutyanskiy, T.V. Murzina, M.V. Sapozhnikov, E.A. Karashtin, V.V. Rogov, A.A. Fraerman, “First and second order in magnetization effects in optical second-harmonic generation from a trilayer magnetic structure”, J. Opt. Soc. Am. B 32 (2), 331-338 (2015).