Coexistence of localized and (induced) itinerant magnetism and heat-capacity anomalies in Gd_1−xY_xNi alloys

Abstract

The results of magnetization (M), electrical resistivity (ρ), and heat-capacity (C) measurements for the alloys, Gd_1−xY_xNi, are reported. The X-ray-diffraction patterns indicate that there is a change in the crystal structure from CrB-type to FeB-type orthorhombic structure for increasing x near x=0.4. GdNi has been known to order ferromagnetically at 70 K and the observed x dependence of T_C and θ_ρ proves that the strength of Gd-Gd exchange interaction is enhanced by a factor of about 1.5 in the FeB structure. The M data suggest that there is an excess moment for the Gd-rich alloys. The observed magnetization behavior is taken as an evidence to show that there is coexistence of localized magnetism (from Gd) and itinerant ferromagnetism of induced-type, presumably from Ni 3d band. There is an enhancement of C with decreasing temperature above T_C over a wide temperature range presumably due to short-range order effects in these alloys.