Observation of field-induced reverse transformation in ferromagnetic shape memory alloy Ni₅₀Mn₃₆Sn₁₄

The structural and magnetic properties of the ferromagnetic Heusler alloy Ni50 Mn36 Sn14 were studied by magnetization and x-ray powder diffraction measurements in fields up to 5 T. The alloy undergoes the martensitic transformation from the L 21 -type cubic structure with the lattice parameter ac =0.5988 nm into an orthorhombic structure with the lattice parameters ao =0.8617 nm, bo =0.5702 nm and co =0.4359 nm at Ms =220 K with a thermal hysteresis of 40 K. The cell volume contracts by 0.37% and the magnetic moment decreases by 50% at Ms. Furthermore, we directly observed the field-induced reverse martensitic transformation.