Magnetic properties of a rapidly quenched Ni–Mn–Ga shape memory alloy

In this work we have studied a magnetic shape memory alloy of composition Ni51Mn28Ga21 prepared by rapid quenching in the form of a ribbon. It belongs to the intermediate Group II, showing a martensitic transformation temperature (TM) around room temperature and usually below TC, the magnetic order one. Magnetic characterisation has been performed in a SQUID magnetometer between 250 and 400 K and fields up to 7 T. The determined Curie temperature is 344 K, as deduced from 25 Oe field measurements. Field induced detwining of the variants has been found at fields of about 2 kOe around room temperature with some hysteresis. Effect of annealing of the sample is also discussed.