ИСТИНА

We report on the comprehensive study of structural, magnetic, magneto-optical and transport properties of Si1-xMnx alloys (x ≈ 0.52-0.55). Stoichiometric MnSi alloys are ferromagnetics with Curie temperature ~ 30 K, while the nonstoichiometric Si1-xMnx (x ≈ 0.52-0.55) were shown to be ferromagnetic at room-temperature [2,3]. Previously we have shown that deviations in composition of films near the stoichiometry lead to a drastic change in transport and magnetic properties of such films. Si1-xMnx films 60–70 nm thick with various Mn (x ≈ 0.52–0.55) content were deposited on Al2O3 (0001) substrates using the pulsed laser deposition (PLD) method. Magnetometry shows the good homogeneity of the film magnetization, the saturation magnetic moment at low temperatures is well described by Bloch law. The presence of different phases with Curie temperature 230 K and 490 K was revealed for x ≈ 0.55. TKE and AHE experimental data were found to be in good correspondence with magnetic properties. We discuss the recent results of detailed comparative study of produced films and analyze the origin of ferromagnetic behaviour, supposing that formation of localized magnetic moments due to nonstoichiometry and their exchange coupling lead to ferromagnetic ordering.