J. Phys. IV France 112 (2003) 985
A first-principles investigation of tetragonal and orthorhombic deformations in the ferromagnetic Heusler alloy Ni 2MnGaA.T. Zayak1, P. Entel1 and J. Hafner2
1 Theoretical Physics, Gerhard-Mercator University, Lotharstr. 1, 47048 Duisburg, Germany
2 Institut für Materialphysik, Universitât Wien, Sensengasse 8/12, 1090 Wien, Austria
Tetragonal and orthorhombic deformations in Ni 2MnGa were studied by using the Density Functional Theory formalism with US GGA pseudopotentials implemented in the VASP code in order to find an optimal geometry of the low-temperature structure. Structural and magnetic parameters of the initial L2 1 structure and elastic constants are in a good agreement with experimental data and previous calculations. Not all of the low-temperature martensitic structures could be reproduced by applying the tetragonal and the orthorhombic deformations. It was argued that the modulation arising from shuffling of atoms is important for these structures. A simple kind of shuffling was studied. That gives experimentally predicted structural instability associated with a soft phonon mode, but does not stabilize any new structures.
© EDP Sciences 2003