Critical Magnetic Thermal Expansivity of RbMnF3

Abstract

Precision measurements of the magnetic thermal expansivity of RbMn${\mathrm{F}}_3$ near its critcal (Néel) temperature are reported. The critical exponents are $\alpha =+0.007\mathrm{}\pm 0.02$ and ${\alpha }^{\prime }=-0.100\mathrm{}\pm 0.03$, in disagreement with scaling predictions. The rounding about $T_c$ due to sample inhomogeneity is observed to be asymmetric.