Extended x-ray absorption fine structure study of MnFeP0.56Si0.44 compound

The MnFeP0.56Si0.44 compound is investigated by x-ray diffraction, magnetic measurements, and x-ray absorption fine structure spectroscopy. It crystallizes in Fe2P-type structure with the lattice parameters a = b = 5.9823 (0) angstrom and c = 3.4551 (1) angstrom and undergoes a first-order phase transition at the Curie temperature of 255 K. The Fe K edge and Mn K edge x-ray absorption fine structure spectra show that Mn atoms mainly reside at 3g sites, while 3f sites are occupied by Fe atoms. The distances between the absorbing Fe atom and the first and second nearest neighbor Fe atoms in a 3f-layer shift from 2.65 angstrom and 4.01 angstrom in the ferromagnetic state to 2.61 angstrom and 3.96 angstrom in the paramagnetic phase. On the other hand, the distance between the 3g-layer and 3f-layer changes a little as 2.66 angstrom-2.73 angstrom below the Curie temperature and 2.68 angstrom-2.75 angstrom above it.