Magnetic specific heat of the nearly-one-dimensional system tetramethyl ammonium nickel trichloride (TMNC)

Abstract

The specific heat of tetramethyl ammonium nickel trichloride (TMNC) for $3.5<T<20$ K has been analyzed using the scaled lattice contribution of the isomorphic cadmium and manganese compounds and a magnetic contribution represented by the Hamiltonian $\mathcal{H}=-2J{\Sigma }_i{\overrightarrow{\mathrm{S}}}_i·{\overrightarrow{\mathrm{S}}}_{i+1\mathrm{}}-D{\Sigma }_i[S_{\mathrm{iz}}^2-\frac{S(S+1\mathrm{})\mathrm{}}{3}]$. The resulting parameter values $\frac{J}{k}=+1.7\mathrm{}\pm 0.3$ K, and $\frac{D}{k}=-3.3\mathrm{}\pm 0.5$ K are qualitatively in agreement with the results from susceptibility measurements.