Influence of the Cu substitution on magnetic properties of Ni–Mn–Sn–B shape memory ribbons

The Heusler alloy Ni50-xCuxMn38Sn12 + By (x = 0, 1, 3 and 5) was successfully produced in ribbon form using melt spinning technique. The magnetic properties of the obtained ribbons were analyzed in detail. In all ribbons, it was detected that the ferromagnetic austenite phase transformed into the weak magnetic martensite phase. A separation between FC and ZFC curves at lower temperatures was found. An increase in the magnetization in FC mode can be attributed to the coexistence of ferromagnetic (FM)/antiferromagnetic (AFM) at martensitic phase. It was found that the transition temperatures shifted to low temperatures with increasing the Cu content. The magnetization results under high magnetic field (10 kOe and 50 kOe) showed a thermal hysteresis between the cooling and heating cycles, which is clear evidence for a first-order transformation in the ribbons. From M–H data, all the ribbons exhibited ferromagnetic behavior at low temperatures below the martensitic transition temperature and paramagnetic behavior at high temperatures above the transition temperature. The results provide us a comprehensive view to reveal the effect of the Cu substitution on the magnetic properties of Ni–Mn-based shape memory ribbons.