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

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 H=-2JÎiS→i•S→i+1- DÎi[Siz2-S(S+1)3]. The resulting parameter values Jk=+1.7±0.3 K, and Dk=-3.3±0.5 K are qualitatively in agreement with the results from susceptibility measurements.