Neutron diffraction study on the magnetic structure of (Fe0.90Cr0.03Ni0.07)2P

Crystal and magnetic structures of (Fe0.90Cr0.03Ni0.07)2P have been investigated using neutron powder diffraction measurements over a temperature range of 10-300K. The system crystallizes in Fe2P type hexagonal structure (P6-bar 2m space group, Z=3) in which Cr atoms occupy the pyramidal FeII site and Ni atoms occupy the tetrahedral FeI site with total preference. Refined values of the cell parameters and atomic positional parameters are quite close to those reported for the parent compound Fe2P. The substituted alloy retains the ferromagnetic order of Fe2P with the moments orienting along [001] direction. There are signatures of the presence of magnetic clusters. The ordered magnetic moments at 10K are 0.88(2)μB and 2.16(5)μB at the two metallic sites FeI and FeII, respectively. These values are close to those reported for Fe2P at 77K. At 297K, which is in the region of ferromagnetic to paramagnetic transition, the moment at FeI site is quite low at 0.14(3)μB but at FeII site, it is still fairly large at 0.67(15)μB