Determination of the anisotropy of (111) textured IrMn films at low thickness

The anisotropy constant $K$ of antiferromagnetic (111) textured IrMn films was determined from the blocking temperature $TB$ of the high field rotational losses of $NiFe∕IrMn(t)$ film systems of low thickness $t⩽2.5nm$⁠. The losses are measured by torquemetry as a function of $t$ and temperature $T$⁠. $TB$ has been calculated using a Stoner-Wohlfarth model adapted to the experiments. From $TB=(0.04∕kB)Ktϕ2$ (⁠$ϕ=grain$ size), we estimate a constant value of $K=(3±1)×105J∕m3$ for $T=10–400K$⁠. The method is applicable also to other measurements of $TB(t)$ and can be modified for other film systems.