Phenomenological Study of Manganese Antimonite Close to the Néel Temperature

Abstract

The anomalous behavior of the frequency $f$ and specific heat ${C_p}$ data for the new layered trigonal ($P\bar{3}1m$) form of manganese antimonite (MnSb2O6) was analyzed by means of the power-law relations with the critical exponent $\alpha $ in the vicinity of the Néel temperature of ${T_{\rm{N}}}$= 8.0 K. While the extracted values of $\alpha $ from both $f$ and ${C_p}$ below $T_{\rm{N}}$ (the same value of 0.06) match exactly the value 1/16 (= 0.06) predicted from the three-dimensional (3-D) Ising model, the extracted value of 0.65 from the ${C_p}$ data above $T_{\rm{N}}$ is much higher than the predicted value of 1/8 (= 0.13) from the 3-D Ising model. As an extension of this work, the temperature dependence of the muon-spin relaxation rate (damping constant) $\lambda $ of MnSb2O6 was calculated from the pseudospin-phonon-coupled (PS) model and the energy fluctuation (EF) model below $T_{\rm{N}}$. Our results are in good agreement with the data. In addition, the activation energy was calculated from the predicted values of $\lambda $ from both PS and EF models for MnSb2O6. Our results indicate an order-disorder-type transition at $T_{\rm{N}}$= 8.0 K for MnSb2O6.