Interfacial magnetization in exchange-coupledFe∕Cr∕Festructures investigated by second harmonic generation

Abstract

We have studied the magnetic field dependences of magnetic optical second harmonic generation ͑SHG͒ in MBE-grown Fe/ Cr/ Fe/ Ag/ GaAs͑100͒ heterostructures displaying both bilinear and biquadratic interlayer exchange coupling. The magnetic field H was applied in the ͑100͒ surface plane along both easy ͓͑001͔͒ and hard ͓͑110͔͒ axes of the in-plane fourfold magnetic anisotropy. The SHG has been measured in reflection at near normal incidence for different polarization combinations ͑pp , ps , ss , sp͒ of the fundamental and second harmonic light in longitudinal and transversal geometries. The magnetic field variation of the SHG signal clearly reflects the field-induced transformations of the magnetic state at the interfaces in the trilayer. It strongly depends on the configuration of light polarization, experimental geometry ͑longitudinal or transversal͒, and orientation of the magnetic field H relative to the crystal axes. In contrast to linear magneto-optical Kerr effect, which is odd in magnetic field, magnetic SHG is either even in H or does not display a definite parity at all, depending on the polarization configuration. We interpret the data based on a model accounting for nonmagnetic and magnetic contributions to SHG from the surface and interfaces described by C 4v point symmetry. Taking into account the changes of the mutual orientation of interfacial magnetizations allows us to describe the general features of the measured field dependences of SHG.

Spin current and second harmonic generation in non-collinear magnetic systems: the hydrodynamic model

“…Therefore, we have an [M 1 × M 2 ] vector in addition to M 1 and M 2 . The polarization properties of the second harmonic generation from a surface for different directions of the magnetization vector are outlined in 47 . It leads from these properties that if the magnetizations of both layers lie in the pump plane of incidence there is no second harmonic signal in the p-polarization from the first or the second layer separately.…”

Interface and bulk magnetization dynamics in biaxial Fe/Cr structures induced by ultrashort optical pulses

“…For the analysis of the experimental results we use expressions linking the MSHG intensity in different polarization combinations with components of the interfacial magnetization M. 15,[28][29][30] We follow the arguments given in Ref. 15, which base the analysis on the use of effective nonlinear susceptibilities ijk eff accounting for ͑i͒ possible differences between the top and bottom interfaces, ͑ii͒ light absorption at the frequencies and 2, and ͑iii͒ angle of incidence close to the surface normal ͑ Ϸ 10°͒.…”

“…The investigation of MSHG in exchange coupled Fe/ Cr/Fe and Fe/Cr structures 15 showed that for incidence angles close to the surface normal the nonlinear response in different polarization combinations ͑pp , ss , ps , sp͒ is related to different in-plane interfacial magnetization components. This feature can be exploited to investigate not only the static but particularly also the dynamical behavior of different in-plane magnetization components at the interface.…”

Anisotropy of magnetic properties in 2D arrays of permalloy antidots

“…It has been successively applied to the visualization of the exchange coupling of magnetic layers separated by a nonmagnetic nanolayer, vortex magnetization of magnetic nanostructures and some other properties of materials with inhomogeneous magnetization [7,8,9,10,11,12]. It was demonstrated for a number of structures that the relative value of the magnetization-induced contribution to the second-order response is typically one or two orders of magnitude larger as compared to the linear optical analogues.…”