Specific heat of nearly-one-dimensional tetramethyl ammonium manganese trichloride (TMMC) and tetramethyl ammonium cadmium trichloride (TMCC)

Abstract

The specific heat of tetramethyl ammonium manganese trichloride and its cadmium isomorph is measured for $2<T<52$ K. The temperature dependence of the lattice specific heat of the cadmium compound could be fitted with an expression based upon a pseudoelastic approach of the lattice vibrations in this low-dimensional system. Application of this approach to the manganese compound yields a magnetic contribution which fits the overall behavior of a one-dimensional Heisenberg model with an intrachain interaction of $\frac{J}{k}=\ensuremath{-}6.7\ifmmode\pm\else\textpm\fi{}0.5$ K. Inspection of the low-temperature region yields a satisfactory agreement with the expression ${C}_{m}=1.1|\frac{\mathrm{kT}}{J}|+0.5{|\frac{\mathrm{kT}}{J}|}^{2}\ensuremath{-}0.13{|\frac{\mathrm{kT}}{J}|}^{3}$, predicted by recent calculations.