Magnetic and Structural Properties of MnCoGe with Minimal Fe and Sn Substitution

The magnetic and structural properties of MnCo0.92Fe0.08Ge1-xSnx (x = 0.02, 0.05, and 0.1) were investigated. A first-order magnetic transition was observed, which was accompanied by the martensitic transformation from a hexagonal Ni2In-type to an orthorhombic TiNiSi-type structure in the vicinity of 320K for x = 0.02 and 170K for x = 0.05 with thermal hysteresis of approximately 20 K. The magnetization of MnCo0.92Fe0.08Ge0.95Sn0.05 was estimated to be 102 Am-2 kg(-1) in 5 T at 10 K. High field magnetization curves up to 55 T for MnCo0.92Fe0.08Ge0.95Sn0.05 indicated the field-induced martensitic transformation. Mossbauer spectroscopy experiments revealed that Fe atoms occupied 79%-85% in the Co-site and 21%-15% in the Mn-site.