The Effect of Partial Substitution of Ni by Co on the Magnetic and Electrical Properties of ${\rm Ni}_{50}{\rm Mn}_{35}{\rm In}_{15}$ Heusler Alloy

In this paper, we have explored the effects of the partial substitution of Ni for a small amount of Co in ${\rm Ni}_{50}{\rm Mn}_{35}{\rm In}_{15}$ on its structural, magnetic, and electrical properties by using room temperature X-ray diffraction, temperature- and field-dependent magnetization, M(T,H), and resistivity $\rho({\rm T},{\rm H})$ measurements in magnetic fields up to 5 T, and in the temperature interval 5–400 K. A small amount of Co ($\sim$ 4%) doping in the Ni site decreases ${\rm T}_{\rm M}$ and increases ${\rm T}_{\rm C}$. For ${\rm Ni}_{48}{\rm Co}_{2}{\rm Mn}_{35}{\rm In}_{15}$, a large MR was found to be about $-$53% at $\Delta{\rm H}=1\ {\rm T}$ (at ${\rm T}=$ 275 K) and more than $-$ 70% at the same temperature for $\Delta{\rm H}=5\ {\rm T}$. The substitution of Co in the Ni position enhances the magnetization jump up to 77 emu/g across the martensitic transformation. Magnetization measurements revealed that the large magnetoresistance value could be due to a metamagnetic-like transition, where the system transforms from a state that contains antiferromagnetically coupled regions to a purely ferromagnetic state. The change in magnetic and electrical properties due to the doping of the Co atom in Ni-Mn-In-based Heusler alloys is discussed in this paper.