Magnetic Properties of (Y_1−xGd_x)Ni₃: A Study on the Localized Moment in a Weak Ferromagnet

Abstract

The magnetization of (Y_1−xGd_x)Ni₃ (0≤x≤0.05) at 6.2 kOe was studied in the temperature range between 4.2 and 295 K. The measurements indicate that the magnetic moments of the Gd ions and the itinerant electrons are coupled antiferromagnetically. The samples for x≥0.033 have compensation points. The magnetization curve for each sample crosses with the curve for the host material at about 60 K. The observed magnetization is analyzed on the basis of the s-f exchange model. By the molecular field approximation applied to the temperature dependence of the magnetization, the value, −0.02 eV, is obtained for the s-f exchange integral J. The amount of the induced moment due to Gd atoms extrapolated to T=0 K is 1.3 μ_B per Gd atom. The existence of a new characteristic temperature T^* in the paramagnetic region is predicted theoretically. The experimental result agrees with the prediction.