Magnetic Behavior of Thin Films of Nickel and Gadolinium Near the Curie Point

Abstract
Magnetization measurements have been made on thin films of nickel and gadolinium near the Curie point using a torque technique. The films were prepared by evaporation in pressures of 10−7 and 10−8 Torr. Most of the measurements were made with a torsion magnetometer and the others with an automatic torquemeter system. The relative magnetization σ near but below Tc is described by σ = D(1−τ)f, where τ = T/Tc. The value of f is obtained by using the procedure of Callen and Callen. Plots of σ(1−f)/fdσ/dτ for nickel films were flat for f = ½ for temperatures 0.90<τf = ⅓ are observed at lower temperatures. Gd films gave f = 0.6 for temperatures 0.8<τ0.9. The ½‐power behavior is in agreement with molecular‐field theory and the Landau theory for second‐order transitions.