Static universality class implied by the critical exponents of Gd

Structural characteristics and available critical exponent measurements fail to distinguish clearly between Ising and Heisenberg critical behavior in Gd. In this context we present a new perturbed {γ}{γ}-angular correlation measurement of the exponent {β} which appears to resolve the ambiguity. From our result, {β}=0.399(16), we conclude that Gd is described by Heisenberg critical behavior for reduced temperatures {ε}>10^-3. This does not exclude crossover to another value for smaller {ε}.