MgO template effect for perpendicular magnetic anisotropy in (001)-textured poly-crystalline MnAlGe films

Magnetic thin films showing high perpendicular magnetic anisotropy, Ku, and low saturation magnetization, Ms, are essential for realizing a small switching current in spintronic devices utilizing the current induced magnetization switching phenomena. The Cu2Sb-type MnAlGe intermetallic compound is a material showing uniaxial magnetocrystalline anisotropy with a relatively low Ms, which is attractive for spintronic application. In this study, the layer thickness dependence of Ku was investigated in poly-crystalline MnAlGe films, and the MgO template effect is discussed to achieve perpendicularly magnetized films in a few-nanometer thickness range. Experimental results suggested that the (001)-texture for the perpendicular magnetization was promoted by the MgO(001) template through the solid-phase epitaxy growth by annealing, which is similar with that in conventionally used CoFeB|MgO layered samples. Ku of about 2 × 106 erg/cm3 was achieved in a 5 nm-thick MnAlGe film using MgO buffer and capping exhibiting a low Ms value of approximately 200 emu/cm3 at room temperature. Although the magnitude of Ku is still in a moderate range, the low Ms is a promising feature for spintronic application.