Observation of a Symmetric Logarithmic Singularity in the Specific Heat of K₂CoF₄

Abstract

Precise measurements of specific heat near the antiferromagnetic transition of a two-dimensional Ising-like magnet K₂CoF₄ are carried out. The results are analyzed using asymptotic critical exponent expressions to obtain its parameters and yield a logarithmically infinite singularity in marked agreement with Onsager’s exact solution for the two-dimensional Ising model.