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 (3) over bar 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 Neel temperature of T-N= 8.0 K. While the extracted values of a from both f and C-p below T-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-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-N. Our results are in good agreement with the data. In addition, the activation energy was calculated from the predicted values of. from both PS and EF models for MnSb2O6. Our results indicate an order-disorder-type transition at T-N = 8.0 K for MnSb2O6.