Magnetic anisotropy peculiarities of high-temperature ferromagnetic MnxSi1−x (x ≈ 0.5) alloy films

Thin films of MnxSi1-xalloys with different Mn concentration x ≈ 0.44-0.63 grown by the pulsed-laser deposition (PLD) method onto the Al2O3(0001) substrate were investigated in the temperature range 4-300 K using ferromagnetic resonance (FMR) measurements in the wide range of frequencies and magnetic fields . For samples with x ≈ 0.52-0.55, FMR data show clear evidence of ferromagnetism (FM) with high Curie temperatures Tc ∼ 300K. These samples demonstrate the complex and unusual character of magnetic anisotropy described in the frame of phenomenological model as a combination of the essential second-order easy-plane anisotropy contribution and the additional fourth-order anisotropy contribution with the easy direction normal to the film plane. We explain the obtained results by a polycrystalline (mosaic) structure of the films caused by the film-substrate lattice mismatch