Magnetic-field-induced strain of Fe–Ni–Ga in single-variant state

The magnetic-field-induced strain (MFIS) and the magnetocrystalline anisotropy in Fe19.3Ni54.2Ga26.5 ferromagnetic shape memory alloy have been investigated in a single-variant state. From the magnetization curves, the magnetocrystalline anisotropy constant K in the single crystal Fe19.3Ni54.2Ga26.5 β′ martensite phase is estimated to be 1.8×106 erg/cm3 at 5 K. In the single-variant martensite phase, the reversible MFIS of 0.02% is observed, and the value of K is reduced with increasing temperature. On the other hand, the magnitude of MFIS increases up to 100 K, and then decreases with increasing temperature. Finally, no MFIS is observed above 150 K. From these data, the condition of K for the MFIS can be confirmed at low temperatures.