Research progress on magnetic random access memory based on Mn-based binary alloys

With the rapid development of the information age, magnetic random access memory (MRAM) has emerged as a hot topic in memory device research due to its advantages of high storage density, fast read/write speeds, and non-volatility. Over the past decade, perpendicularly magnetized Mn-based binary alloys, including MnxGa and MnxAl, have attracted significant attention as ideal electrode materials for MRAM. These materials exhibit exceptionally large perpendicular magnetic anisotropy (PMA), high spin polarization, and low magnetic damping constants. This paper reviews recent research progress on the crystal structures and magnetic properties of perpendicularly magnetized Mn-based binary alloy thin films, as well as their applications in magnetic tunnel junctions (MTJs) and spin-orbit torque (SOT) devices. We discuss in detail the lattice structure, epitaxial growth methods, magnetic properties and exchange coupling behavior of L10 and D022 phase MnxGa and MnxAl films, with a focus on the influence of growth conditions on key parameters such as PMA, damping factor, and spin polarization. We also summarize the research on MnxGa and MnxAl-based MTJs, including experimental and theoretical analyses of tunnelling magnetoresistance (TMR), and explore techniques to improve the TMR ratio through interface engineering, such as introducing Heusler alloy buffer layer or metal interlayers. The constraints imposed by lattice mismatch and interface defects on device performance are analyzed. Additionally, we explain the SOT-driven magnetization switching phenomenon in Mn-based binary alloys, especially the field-free magnetization switching observed in D022-Mn3Ga/Pt, L10-MnGa/FeMn, and related bilayers, revealing the critical role of interface coupling and material design in reducing the switching current density and improving switching efficiency.