Faraday rotation near the Curie point of EuO

The static magnetic properties of EuO near the Curie point have been measured using Faraday rotation. Comparison between magnetometer data reveals a small nonlinear term in the relation between rotation and magnetization. With this correction, our results yield critical parameters β=0.370±0.006, B=1.10±0.04, γ=1.30±0.02, and Γ=0.397±0.012. The value of γ agrees with other static experiments, but disagrees with neutron-scattering measurements and with theory. All the data can be scaled using these exponents, and are consistent with the two proposed parametric equations of state, with coefficients a1=2.56, k1=1.025 and a2=1.78, k2=0.718. Our data predict specific-heat parameters α=-0.04±0.03 and AA′=1.31±0.05, in agreement with experimental results analyzed with nonsingular correction terms.