NEW L21-TYPE INTERMETALLIC COMPOUND IN IR-MN-SN SYSTEM AND ITS MAGNETIC-PROPERTIES

Crystal structures and magnetic properties of Ir-Mn-Sn alloys have been investigated by means of X-ray diffraction and magnetic analysis. It has been found that a new L2(1)-type intermetallic compound (Heusler alloy) of Ir1.8Mn1.2Sn exists in the Ir-Mn-Sn system and forms a solid solution in a wide composition range, where Ir1.8Mn1.2Sn to Ir1.6Mn1.4Sn have lattice parameters of 0.6204 to 0.6189 nm, magnetic moments of 3.2 to 2.6 mu(B)/Mn and Curie temperatures of 342 to 265 K. The typical Ir1.8Mn1.2Sn compound has a lattice parameter of 0.6204 nm, a magnetic moment of 3.38 mu(B)/Mn at absolute zero Kelvin and a Curie temperature of 342 K. The magnetization and Curie temperature of their alloys decrease with decreasing lattice parameters, which depend on Mn-Mn interatomic distance remakably. The solid solution of the C1-type has been obtained near the composition of equi-atomic ratio, but their alloys have not characteristic values of the ferromagnetic C1-type compounds.