Room temperature growth of ultrathin ordered MnGa films on a CoGa buffer layer

Tetragonal ultrathin (1-5 nm) ordered MnGa films on a CsCl-type CoGa buffer layer were fabricated by a sputtering method. The (001)-CoGa layer was first deposited on a Cr-buffered MgO substrate and then annealed in-situ at 500 degrees C. The ultrathin MnGa film deposited on the CoGa buffer layer formed the L1(0) structure with very small roughness even when grown at room temperature. In addition, the films showed well-squared perpendicular magnetization hysteresis curves even when the film thickness was as little as 1 nm. The obtained results are important for the development of the MnGa-based spin-transfer torque devices for Gbit class magnetic random access memory and high frequency applications. (C) 2016 The Japan Society of Applied Physics