Investigation of Scaling Laws by Critical Neutron Scattering from Beta-Brass

Using a Cu⁶⁵-Zn β-brass crystal, the critical scattering of neutrons has been studied, both above and below Tc. The staggered susceptibilities χ vary as C₊(TTc-1)^-γ and C_-(1-TTc)^-γ^', respectively. We find that γ=γ^' within an accuracy of 3%, in agreement with the scaling hypothesis of static critical phenomena; and that C₊C_-=5.46±0.05, in excellent agreement with the recent parametric representation theory of Schofield and in fair agreement with the results of series expansions by Essam and Hunter. For fixed q, a flat maximum is observed in the wave-vector-dependent susceptibility χ(q, T) at temperatures which agree well with the predictions of Fisher and Burford.