  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.
