The crystal and magnetic structure of the magnetocaloric compound FeMnP0.5Si0.5

The crystal and magnetic structure of the magnetocaloric compound FeMnP0.5Si0.5 has been studied by means of neutron and X-ray powder diffraction. Single phase samples of nominal composition FeMnP0.5Si0.5 have been prepared by the drop synthesis method. The compound crystallizes in the Fe2P-type structure (P6¯2m) with the magnetic moments aligned along the a-axis. It is found that the Fe atoms are mainly situated in the tetrahedral 3g site while the Mn atoms prefer the pyramidal 3f position. The material is ferromagnetic (TC=382K) and at 296K the total magnetic moment is 4.4μB/f.u. It is shown that the magnetic moment in the 3f site is larger (2.5μB) than in the 3g site (1.9μB).