Magnetic properties and domain structure of magnetic shape memory Ni-Mn-Gaalloy

Magnetic domain structures of single-crystalline Ni48Mn31Ga21 prism with {1 00} faces was studied using scanning electron microscopy and by Bitter tech nique. The sample faces parallel to magnetizing direction contain more or l ess a stripe domain structure with 180(-) walls. On the face perpendicular to magnetizing direction, the labyrinth domain structure is established due to out of plane magnetization under strong uniaxial anisotropy. Residual m artensitic bands on the same sample face. however, owing to different cryst al orientation, contain stripe domains. Magnetization curves of the prism e xhibit an abrupt magnetization change and a transient hysteresis in the fir st quadrant. The abrupt magnetization change is due to field-induced rearra ngement of martensitic twin variants preceded by magnetization rotation. (C ) 2001 Elsevier Science B.V. All rights reserved.