High-temperature ferromagnetism of Si1 − x Mn x films fabricated by laser deposition using the droplet velocity separation technique

The transport and magnetic properties of Si1 − x Mn x films of thickness 55–70 nm with various Mn content (x = 0.44–0.6) are studied in the temperature range of 5–400 K and in magnetic fields up to 2 T. The films are grown by pulsed laser deposition on Al2O3 (0001) substrates at a temperature of 340°C using velocity separation of deposited particles. The films exhibit metal conductivity and the resistivity ρ = (2−8) × 10−4 Ω cm, typical of highly degenerate semiconductors. It is found that the anomalous component of the Hall effect dominates over the normal component at T = 300 K for the Si1 − x Mn x alloy with x ≈ 0.5, and that the Curie temperature significantly exceeds room temperature and is estimated as ∼500 K from magnetization measurements (for MnSi silicide the Curie temperature is T C = 30 K). It is shown that the anomalous component of the Hall conductivity at low temperatures is controlled by “side-jump” and (or) “intrinsic” mechanisms independent on the carrier scattering time. The results are explained by features of the formation of defects with localized magnetic moments in the case of Si1 − x Mn x films with x ≈ 0.5 and by the significant role of matrix spin fluctuations in the exchange between these defects.