Critical End Point in CeSb under Uniaxial Pressure Parallel to [001]

The effects of uniaxial pressure parallel to [001] on the magnetic ordering and on the critical fluctuations of CeSb have been studied by neutron diffraction and diffuse critical neutron scattering. We find that the system exhibits a critical end point at p=2.0±0.3 kbar and T=18.1±0.2 K, which is understood in terms of competing bilinear and higher-degree magnetic interactions favoring antiferromagnetic type-I ordering with a second-order transition and a modulated ordering with a first-order transition, respectively.