Magnetic anisotropy peculiarities of high-temperature ferromagnetic Mn

Thin films of MnxSi1−x alloys with different Mn concentration $x\approx0.44\text{--}0.63$ 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 $(f = 7\text{--}60\ \text{GHz})$ and magnetic fields $(H = 0\text{--}30\ \text{kOe})$ . For samples with $x\approx0.52\text{--}0.55$ , FMR data show clear evidence of ferromagnetism (FM) with high Curie temperatures $T_\mathrm{C} \sim 300\ \text{K}$ . 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

Anomalous Hall effect in polycrystalline Mnx Si1_x (x = 0:5) films with the self-organized distribution of crystallites over their shapes and sizes

International audienc

Ferromagnetism of MnxSi1-x(x ∼ 0.5) films grown in the shadow geometry by pulsed laser deposition method

The results of a comprehensive study of magnetic, magneto-transport and structural properties of nonstoichiometric MnxSi1-x (x ≈ 0.51-0.52) films grown by the Pulsed Laser Deposition (PLD) technique onto Al2O3(0001) single crystal substrates at T = 340°C are present. A highlight of used PLD method is the non-conventional (“shadow”) geometry with Kr as a scattering gas during the sample growth. It is found that the films exhibit high-temperature (HT) ferromagnetism (FM) with the Curie temperature TC ∼ 370 K accompanied by positive sign anomalous Hall effect (AHE); they also reveal the polycrystalline structure with unusual distribution of grains in size and shape. It is established that HT FM order is originated from the bottom interfacial self-organizing nanocrystalline layer. The upper layer adopted columnar structure with the lateral grain size ≥50 nm, possesses low temperature (LT) type of FM order with Tc ≈ 46 K and contributes essentially to the magnetization at T ≤ 50 K. Under these conditions, AHE changes its sign from positive to negative at T ≤ 30K. We attribute observed properties to the synergy of distribution of MnxSi1-x crystallites in size and shape as well as peculiarities of defect-induced FM order in shadow geometry grown polycrystalline MnxSi1-x (x ∼ 0.5) films

Anomalous Hall effect in polycrystalline Mnx Si1_x (x = 0:5) films with the self-organized distribution of crystallites over their shapes and sizes

International audienc