Heat capacity of FeF2near the antiferromagnetic transition

Abstract

Already existing results for $C_p$ of the uniaxial antiferromagnet Fe${\mathrm{F}}_2$ near the transition temperature are shown to yield the exponents $\alpha ={\alpha }^{\prime }=0.16\mathrm{}$ and the amplitude ratio $\frac{A}{A^{\prime }}=0.53\mathrm{}$. As expected from theory, these results are very different from those for the isotropic antiferromagnet RbMn${\mathrm{F}}_3$, but they are consistent with the exponents and amplitude ratio obtained for liquid-gas critical points, and thereby support the theoretically predicted universality of critical-point parameters.