High magnetic field treatment of variants in ferromagnetic shape memory alloy Ni₅₀Mn_28.5Ga_21.5 single crystal and magnetostrain

Ni₅₀Mn_28.5Ga_21.5 single crystal with size of φ7 mm × 60 mm was prepared by optical floating zone-melting method, from which two experimental single crystal samples with the sizes of 8.1 mm × 4.3 mm × 4.4 mm and φ7 mm × 38.9 mm were cut by spark. A 10 T high pulsed magnetic field was used to treat variants, and a near single variant was obtained, 5.2% giant magnetostrain was achieved in the treated single crystal. The effect of the pressure on the magnetostrain was investigated, which showed that with increasing the compression stress, the critical magnetic field for the magnetostrain jump increased and the magnetostrain was decreased.