Magnetisation and ESR Studies of Gd(Ni 1− x Rh x ) 5 Compounds

Magnetisation and electron spin resonance measurements are performed on Gd(Ni 1− x Rh x ) 5 compounds with x = 0, 0.1, 0.2, 0.3, 0.5, and 1.0. In the ordered state the value of the spontaneous moments is 6.5 μ B /f.u. in GdNi 5 , rising to 6.7 μ B /f.u. at the GdRh 5 end of the series. Both θ p and T c show rapid variation with Rh substitution, particularly at the GdNi 5 end of the series where dθ p / dc ≈ 1.1 K/at% Rh. The ESR measurements indicate that the system is bottlenecked. The substitution of Rh for Ni reduces the slope of the linewidth from 7 × 10 −4 T/K in GdNi 5 to 4 × 10 −4 T/K in GdRh 5 and raises the g ‐value from 1.923 in GdNi 5 to about 2.000 at the GdRh 5 end of the series; both indicative of a change in the character of the conduction electrons from predominantly d‐like in GdNi 5 to predominantly s‐like in GdRh 5 . From the g ‐shift a value of J = −0.005 eV is obtained for the effective exchange integral. Both, ESR and magnetic data indicate that the density of d‐states goes through a minimum close to the GdNi 5 end of the series.