Control of the in-plane anisotropy in off-stoichiometric NiMnSb

NiMnSb is a ferromagnetic half-metal which, because of its rich anisotropy and very low Gilbert damping, is a promising candidate for applications in information technologies. We have investigated the in-plane anisotropy properties of thin, MBE-grown NiMnSb films as a function of their Mn concentration. Using ferromagnetic resonance (FMR) to determine the uniaxial and four-fold anisotropy fields, 2KU/Ms and 2K1/Ms, we find that a small variation in composition is sufficient to change the film from primarily four-fold to primarily uniaxial behavior, allowing for continuous tuning of the anisotropy. This provides valuable flexibility in designing new device geometries.