Magnetic and magnetomechanical properties of Ni2MnGa

Magnetocrystalline anisotropy and magnetostrictive properties are reported for the austenitic and martensitic phases of ferromagnetic shape memory Heu sler alloy Ni2MnGa. In the low-temperature martensitic phase, the phenomeno n of field-induced variant rearrangement provides a mechanism which can pro duce large strains, while at the same time causing anomalous effects in the apparent anisotropy. These anomalies and their effects on measured M-H and torque curves are clarified. Magnetomechanical experiments were performed in the martensitic phase to characterize the work output of a suitably orie nted specimen at various stresses, and with proper stress biasing of the in itial microstructure produced the largest magnetostrictive strains to date of 4.3%. (C) 1999 Elsevier Science B.V. All rights reserved.