On the Ising-Heisenberg model with the doubly decorated network structure I

Using an exact mapping transformation method, magnetic properties of a spin-(1)/(2) and spin-1 doubly decorated Ising-Heisenberg model are investigated in detail. By assuming that both interaction parameters are ferromagnetic, we found in addition to an usual ferromagnetic phase another two phases with a nontrivial long-range order. (C) 2003 Elsevier B.V. All rights reserved.