Oriented single crystals of Ni–Mn–Ga with very low switching field

Abstract

Ni–Mn–Ga single crystals were grown from an oriented seed using a modified Bridgman method. The grown crystals can be oriented very easily for final preparation of magnetic shape memory (MSM) elements with all faces parallel to {100}. The twinning stress depends on the orientation of the twin habit plane. For type I twin boundaries with traces perpendicular to the sample edge, the equivalent stress to move the twin boundary was 0.9MPa. For type II twin boundaries with traces slightly inclined to those of type I twin boundaries, the equivalent stress to move the twin boundary was 0.01MPa. The presented method of growing and processing Ni–Mn–Ga single crystals is more efficient than existing methods and produces high-quality MSM elements.