Paramagnetic Susceptibility of GdNi3

Abstract

Using the molecular field theory, the paramagnetic susceptibility of ferromagnetic rare earth-transition metal compounds is investigated. When the itinerant electron's susceptibility χ c obeys the C-W (Curie-Weiss) law, the total susceptibility χ obeys an approximate C-W law at sufficiently high temperatures and, if the s – f exchange integral J is negative, the Curie point T c is higher than the paramagnetic Curie point Θ p . However, the relation between the induced spin polarization coefficient α and 1/χ vs T curve is intricate. This prediction is confirmed by experiments on the susceptibility of GdNi 3 ( T c = 113 K) in the temperature range from 113 K to 700 K. Above around 340 K χ obeys an approximate C-W law with Θ p =70 K and p eff = 7.99 which is the effective Bohr magneton number. The exchange integral J is negative and the value of α at T c is roughly estimated to be -0.08.