Magnetic Excitations and the Curie Temperature of Decamethylchromocenium Tetracyanoethylenide

We describe the molecular ferromagnet decamethylchromocenium tetracyanoethanide [C_rC_p2^*] [TCNE] by a quasi-one-dimensional alternating-spin model with ferromagnetic exchange interaction. The spin-wave theory is used to discuss the magnetic excitation of the molecular ferromagnet. We obtain the magnetizations corresponding to different external magnetic fields without interchain exchange interaction which is consistent with the experimental results. The formula of the Curie temperature T_c is obtained by using the thermodynamic Green's function method. It is found to be related to the spin of donors, to the intrachain exchange interaction and to the spatial anisotropic parameter. The result obtained by this T_c formula is consistent with the experimental result T_c = 3.6 K for [C_rC_p2^*][TCNE].