  We report here non-collinear magnetic configurations in the Heusler alloys
Ni2MnGa and Ni2MnAl which are interesting in the context of the magnetic shape
memory effect. The total energies for different spin spirals are calculated and
the ground state magnetic structures are identified. The calculated dispersion
curves are used to estimate the Curie temperature which is found to be in good
agreement with experiments. In addition, the variation of the magnetic moment
as a function of the spiral structure is studied. Most of the variation is
associated with Ni, and symmetry constraints relevant for the magnetization are
identified. Based on the calculated results, the effect of the constituent
atoms in determining the Curie temperature is discussed.
