Phase Transitions in Two-Dimensional Random Antiferromagnets Rb₂Co_cNi_1−cF₄

Abstract

Neutron scattering and specific heat capacity measurements were made on a two-dimensional randomly mixed antiferromagnets Rb₂Co_cNi_1−cF₂. The experimental results show a sharp phase transition which has not been ever found in the random magnetic systems. This gives an answer to a long-lived question whether or not a sharp phase transition occurs in a homogeneously random magnetic system. The critical exponents α, β, ν and γ of Rb₂Co_cNi_1−cF₂ is identical with those of two-dimensional Ising model.