Switchable Ni-Mn-Ga Heusler nanocrystals

We examined bulklike Heusler nanocrystals using real-space pseudopotentials constructed within density functional theory. The nanocrystals were made of various compositions of Ni-Mn-Ga in the size range from 15 up to 169 atoms. Among these compositions, the closest to the stoichiometric Ni2MnGa were found to be the most stable. The Ni-based nanocrystals retained a tendency for tetragonal distortion, which is inherited from the bulk properties. Surface effects suppress the tetragonal structure in the smaller Ni-based nanocrystals, while bigger nanocrystals develop a bulklike tetragonal distortion. We suggest the possibility of switchable Ni-Mn-Ga nanocrystals, which could be utilized for magnetic nanoshape-memory applications. (c) 2008 American Institute of Physics. [DOI: 10.1063/1.2988189]