Sn-doping induced modification of the magnetic and magnetocaloric properties in MnNiGe alloy.

Sn-doped MnNiGe alloy of nominal composition MnNiGe 0.915 Sn 0.085 has been examined through structural and magnetic investigations. Sn-doping stabilizes the hexagonal structure (with P 6 3 / m m c space group) at room temperature. On cooling from room temperature, it first orders antiferromagnetically (with commensurate structure) around 185 K. Further cooling results in a structural change of martensitic type around 145 K. The observed structural transition is also found to be associated with a simultaneous magnetic transition from high temperature commensurate antiferromagnetic state to low temperature incommensurate antiferromagnetic state. Both conventional and inverse magnetocaloric effect (MCE), with peak values of −6.01 J/kg-K and 6.56 J/kg-K for 0 to 5 tesla of changing magnetic field, have been visible around the magnetic and structural transitions, respectively. A significant effect of external hydrostatic pressure on the magnetic and MCE behaviors has also been observed. • Sn-doped MnNiGe alloy stabilizes hexagonal (P 6 3 / m m c) structure at room temperature. • Sn-doping results in a significant decrease in martensitic transition temperature. • Both conventional and inverse magnetocaloric effects (MCE) have been observed. • External hydrostatic pressure affects significantly on magnetic and MCE behavior. [ABSTRACT FROM AUTHOR]