Ultra-thin spin-valve structures grown on the surface-reconstructed GaAs substrate

Abstract

We studied magnetic anisotropies of epitaxial, ultra-thin iron spinvalve structures grown on surface reconstructed GaAs substrates. The ferromagnetic resonance (FMR) technique has been exploited to determine magnetic parameters of the ferromagnetic films in the temperature range 4-300 K. The unusual and unexpected angular dependence of FMR spectra allowed us to build and verify a model describing the magnetic anisotropy of the studied systems. Switching of the principal anisotropy axes of the second layer has been observed. It was attributed to a drastic relaxation of the uniaxial component of anisotropy induced by the surface reconstruction of the substrate. The linear variation of magnetic anisotropy parameters with temperature has been observed. The results on temperature dependence are discussed in terms of thermal expansion induced magneto-elastic anisotropies.