Modulations in martensitic Heusler alloys originate from nanotwin ordering.

ABSTRACT: Heusler alloys exhibiting magnetic and martensitic transitions enable applications like magnetocaloric refrigeration and actuation based on the magnetic shape memory effect. Their outstanding functional properties depend on low hysteresis losses and low actuation fields. These are only achieved if the atomic positions deviate from a tetragonal lattice by periodic displacements. The origin of the so-called modulated structures is the subject of much controversy: They are either explained by phonon softening or adaptive nanotwinning. Here we used large-scale density functional theory calculations on the Ni₂MnGa prototype system to demonstrate interaction energy between twin boundaries. Minimizing the interaction energy resulted in the experimentally observed ordered modulations at

SUBMITTER: Gruner ME 

PROVIDER: S-EPMC5981613 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature