  A fundamental question in the study of ferromagnetic shap ememory alloys is
the nature of magnetoelastic coupling and the extent it drives the structural
transformation. This question also holds the key to developing new and
optimized alloys that combine high strains at low switching field. In the
present study it is shown that the reconfiguration of the micromagnetic
structure is enslaved to and follows the martensitic transformation in these
alloys using the NiMnGa and FePd alloy systems. This is determined by
developing a new, high speed electronic method to study the temperature
dependence of domain dynamics, called magnetic transition spectra. The sequence
of magnetic and structural transition was found to be as follows. For cooling,
structural transition followed by magnetic transition and for heating, magnetic
transition followed by structural transition.

Materials Science