Magnetization and Ni-61 Mossbauer effect study of the ternary arsenide CrNiAs

摘要

The results of x-ray diffraction, dc magnetization, and Ni-61 Mossbauer spectroscopy studies of the ternary arsenide CrNiAs are reported. This compound crystallizes in the orthorhombic Fe2P-type structure (space group P(6) over bar 2m) with the lattice parameters a = 6.1128(2) angstrom and c = 3.6585(1) angstrom. CrNiAs is a mean-field ferromagnet with Curie temperature T-C = 171.9(1) K and the critical exponents beta = 0.514(18), gamma = 1.010(16), and delta = 2.922(10). The temperature dependence of the magnetic susceptibility above T-C follows the modified Curie-Weiss law with a paramagnetic Curie temperature of 176.0(3) K and effective magnetic moment per transition metal atom of 2.42(1) mu(B). The magnetic moment per formula unit at 4.2 K is found to be 1.114(33) mu(B). The hyperfine magnetic field at Ni-61 nuclei at 4.2 K of 41.5(1.0) kOe implies that the Ni atoms carry a magnetic moment of 0.15(3) mu(B), and that the moment carried by the Cr atoms is 0.95(6) mu(B). The Debye temperature of CrNiAs is 221(1) K.