Heat capacity and critical behavior of hexagonalYMnO3

Abstract

We report heat capacity $({C}_{p})$ measurements on high-quality single crystals of hexagonal $\mathrm{Y}\mathrm{Mn}{\mathrm{O}}_{3}$, a ferroelectric and frustrated triangular antiferromagnetic (AF) compound. The obtained values of the critical exponent $\ensuremath{\alpha}$ and amplitude ratio ${A}^{+}∕{A}^{\ensuremath{-}}$ for the AF transition are in good agreement with the standard three-dimensional Heisenberg universality class, and not with a chiral universality class associated with the 120\ifmmode^\circ\else\textdegree\fi{} spin structure. The low-temperature ${C}_{p}$ deviation from the Debye law can be adequately fitted with a single Einstein contribution, indicating that there is no evidence of the anomalous magnetic contributions reported earlier. We also suggest that there is no intrinsic linear term in the low-temperature ${C}_{p}$. These results are consistent with conventional long-range AF ordering in $\mathrm{Y}\mathrm{Mn}{\mathrm{O}}_{3}$.