Lattice Location Effect of Ni50Mn36Sn14 Heusler Alloy

The magnetic properties of Ni50Mn36Sn14 Heusler alloy with L21 structure (L21-NiMnSn HA) are investigated by using the Kaneyoshi approach (KA) within the effective field theory. Mn atoms have two different magnetic properties, and Sn atoms also have two different magnetic properties, according to the lattice location. The L21-NiMnSn HA and its components (Mn1, Mn2, Sn1, Sn2, and Ni) exhibit a second-order phase transition from the ferromagnetic phase to the paramagnetic phase at TC = 2.824. The magnetizations of the HA are obtained as Sn2 > Ni > Mn2 > L21-NiMnSn HA > Sn1 > Mn1 at T < TC. We suggest that the magnetizations of the HA decrease from that of its core atom to its corner atoms. We refer to the different magnetization behavior of the Mn atoms and the Sn atoms of the HA as “lattice location effect (LLE)” because the magnetic difference of the Mn atoms and the Sn atoms of the HA results from their lattice location on the L21 structure. While the coercive fields are the same with each other, their remanence magnetizations are different. Our theoretical results of M(T) and M(H) of L21-NiMnSn HA are in quantitatively good agreement with some experimental results of NiMnSn alloys. Furthermore, the magnetization critical exponent is obtained. Its value is in good agreement with some experimental results and the mean field theory. This case indicates that the model exhibits a universal critical behavior.