Critical behavior of the order-parameter–conserving antiferromagnet CeAs

Neutron diffraction and diffuse-critical-neutron-scattering experiments in CeAs reveal most unusual critical phenomena. Below ${\mathrm{T}}_{\mathrm{N}}$=8.5±0.1 K long-range antiferromagnetic ordering is realized, but there exist short-range ordered critical spin fluctuations which exhibit a maximum at ${\mathrm{T}}^{\mathrm{*}}$=7.3±0.1 K much below ${\mathrm{T}}_{\mathrm{N}}$. These fluctuations predominantly involve the direction of the spins and drastically depress the development of the single component of the mean staggered moment giving rise to an apparent exponent β>1. .AE