Co-doping effect on the martensitic transformation and magnetic properties of Ni49Mn39Sn12 alloy

The effect of 2 at% Co doping in a Ni49Mn39Sn12 alloy is investigated in the present work. Experimental results show that both alloys undergo a ferromagnetic-paramagnetic transition for the martensite, and then to the paramagnetic austenite upon heating. The characteristic temperatures of martensitic transformation increase about 25 K with 2 at% Co doping, while the martensite remains its four-layered orthorhombic structure. It is noted that the magnetization discrepancy between the martensite and the austenite across the martensitic transformation remarkably expands. It is promising that the Co doping enhances the magnetocaloric properties, although the refrigeration capacity of the present studied alloys is not high enough due to the absence of ferromagnetic austenite.