The formation of stable Co/Co2MnSn two phase magnets

The phase equilibria in the system Co-Mn-Sn have been studied with compositions along the join Co-CoMnSn. This is part of an effort to form a macroscopic ferrimagnet with two metallic ferromagnetic phases, Co and Co2MnSn. As-cast are melted alloys have been made with Co compositions from 33 to 78 at. %. Three different phase and magnetization regions are observed with increasing Co composition. Cobalt becomes the primary phase at more than 71 at. % Co and crystallizes out of a Co2MnSn rich matrix. It is shown from x-ray diffraction analysis and the T-c change with Co compositions that the Co phase in Co2MnSn matrix is probably a Go-Mn solid solution. From the break in the magnetization vs temperature curves of two phase magnets with two different compositions, Curie temperatures are determined as approximately 160 degrees C and 175 degrees C for the Go-Mn solid solution phase. The exchange coupling at phase boundary is proposed by the analysis of coercivity vs temperature data. (C) 1996 American Institute of Physics.