A DFT study of L10-MnAl thin-films: Exploring the impact of strain, buffer, and capping layers on magnetic anisotropy and Gilbert damping

Abstract

This work studies the magnetic properties of stoichiometric L10-MnAl thin-films, emphasizing the calculation of the magnetocrystalline anisotropy energy (MAE) and Gilbert damping (α), using Density Functional Theory (DFT). It has been shown that as the film thickness increases, MAE/f.u. in MnAl thin-films converges to the bulk value. The dependency of α on electron scattering rate, which describes the average carrier-lifetime, shows that α also converges to bulk with increasing film thickness. We also report the influence of strain on the magnetic properties of MnAl thin-films, focusing on the significant impact on MAE and α. Finally, we shift our focus to the interfacial effects on MnAl thin-films in magnetic tunnel junctions (MTJs), primarily to learn how different layers within these junctions affect these spin dynamical properties. We have analyzed two distinct arrangements, namely, the CoAl(and CoGa)/MnAl/MgO and MgO/MnAl/capping material structures, where the capping materials include heavy transition metals like Ta, Mo, W, Pt, Pd, and Au. We demonstrate that enhancing the MAE and stability using proper buffer and capping layers is feasible, considering the hybridization and lattice mismatch-induced strain. These findings help to optimize the MTJ design for greater functionality in spintronic devices and emphasize how crucial MnAl ferromagnets will be for fabricating next-generation nanoscale spintronic devices like spin-transfer-torque magnetic random access memory.