Hyperfine magnetic fields in Fe−Co alloys and their temperature dependences

We obtained ⁵⁷Fe hyperfine field parameters from Fe_(1−x)-Co_ x alloys (0≤x≤0.6) from 77 K to 900 K. We first discuss the origin of the low temperature hyperfine fields in terms of the 3d and 4s electrons at ⁵⁷Fe atoms. The ⁵⁷Fe hyperfine magnetic field (hmf) of Fe-Co alloys depends more weakly on temperature than the hmf of pure Fe. This temperature dependence occurs because the alignment of the magnetic moments at both the Fe atoms and at the Co atoms depend on temperature in the same way as the bulk magnetization of Fe-Co alloys.