Cubic-type Heusler compound Mn₂FeGa thin film with strain-induced large perpendicular magnetic anisotropy

This study reports the development of ferrimagnetic cubic Heusler compound Mn(2)FexGa (MFG) thin films with large perpendicular magnetic anisotropy (PMA). By growing MFG on a Cr buffer layer, a cubic X-a phase with a tetragonal distortion c/alpha approximate to AP; 1.04 induced by the buffer layer was obtained in the range of x = 1.0-1.3, leading to large PMA which exceeds 0.75 MJ m(-3) in stoichiometric Mn2FeGa (x = 1). Synchrotron Mossbauer spectroscopy revealed that these cubic MFG thin films show good chemical ordering close to the X-a-ordered state. First-principles calculations demonstrated that, in X-a-ordered cubic MFG, the characteristic electronic structure of Fe around the Fermi level causes a large uniaxial magnetocrystalline anisotropy under the tetragonal strain consistent with experiment. The half-metallic-like band structure of cubic MFG was also shown to be preserved under the strain. Cubic Mn2FeGa with its small saturation magnetization, large PMA, and possibility of being highly spin polarized make this material an ideal candidate for the development of magnetic random-access memory and other spintronic devices.