Observation of an unusual magnetic phase transition in NdSn3

Abstract
We report a neutron-diffraction study of the antiferromagnetic phase transition in NdSn3. The staggered magnetization is a continuous, S-shaped function of temperature with long-range order persisting well above an "apparent" transition temperature. The transition exhibits no measurable hysteresis or critical scattering. This behavior is probably related to the fact that the corresponding n=6 Ginzburg-Landau-Wilson Hamiltonian possesses no stable fixed point.