Current-Induced Magnetization Switching Behavior in Perpendicular Magnetized L10-MnAl/B2-CoGa Bilayer

Abstract

Rare-earth-free Mn-based binary alloy L1₀-MnAl with bulk perpendicular magnetic anisotropy (PMA) holds promise for high-performance magnetic random access memory (MRAM) devices driven by spin-orbit torque (SOT). However, the lattice-mismatch issue makes it challenging to place conventional spin current sources, such as heavy metals, between L1₀-MnAl layers and substrates. In this work, we propose a solution by using the B2-CoGa alloy as the spin current source. The lattice-matching enables high-quality epitaxial growth of 2-nm-thick L1₀-MnAl on B2-CoGa, and the L1₀-MnAl exhibits a large PMA constant of 1.04 × 10⁶ J/m³. Subsequently, the considerable spin Hall effect in B2-CoGa enables the achievement of SOT-induced deterministic magnetization switching. Moreover, we quantitatively determine the SOT efficiency in the bilayer. Furthermore, we design an L1₀-MnAl/B2-CoGa/Co₂MnGa structure to achieve field-free magnetic switching. Our results provide valuable insights for achieving high-performance SOT-MRAM devices based on L1₀-MnAl alloy.