HYPERFINE FIELD AND MAGNETIC-BEHAVIOR OF HEUSLER ALLOYS

The hyperfine fields and Curie temperatures of the Heusler alloys (X 2MnZ) are analyzed and show that: (1) The s-conduction electron polarization (sCEP) is essentially independent of the X or Z element. It is also independent of the difference in the number of valence electrons between a Cd impurity, at a Z site and the Z atom it replaces. This behavior is in contradiction to the basic assumptions made in the charge perturbation models for hyperfine fields but in agreement with the assumptions of the volume overlap model. (2) The behavior of the Curie temperature shows that it is the d-conduction electron polarization not the sCEP that dominates the coupling between the magnetic Mn atoms in the ferromagnetic Heusler alloys.