Ferromagnetic δ-Mn1-x Gax Thin Films with Perpendicular Anisotropy

We report the structure and properties of the thermodynamically stable ε-phase Mn1–x Ga x . single crystal thin films grown on GaAs. X-ray θ–2θ scans and grazing-incidence scattering measurements confirmed that the unit cell of this phase is tetragonal (a = 0.279 nm, c = 0.351 nm) and grows with the c-axis oriented normal to the {001} GaAs substrate surface. X-ray emission spectroscopy confirmed the composition to be 62 ± 2% Mn. Polar Kerr rotation, SQUID and vibrating sample magnetometer measurements with the field applied along the thin-film normal showed nearly perfect square hysteresis loops confirming perpendicular anisotropy of the films. The film exhibits a Kerr rotation angle of ~0.1° at 820 nm, a coercivity of 6.27 kOe and a saturation magnetization of 460 emu/cm3. The optical reflectivity of the film was 65–70% over a broad range of wavelengths. This unique set of properties make it a very promising material for magnetooptic recording with the additional potential of integrating semiconductor/magnetic devices by suitable patterning techniques.