Magnetic properties of a double-layered film on a honeycomb lattice

Molecular-based magnetic materials AFe^IIFe^III(C₂O₄)₃ (A=N(n-C_nH_2n+1)₄, n=3-5) have been widely used in the thermo-magnetic field, which attract much attention from researchers in experiment and theory. Various methods such as Monte Carlo simulation [1], Green function theory [2], Effective-field theory [3] have been used to investigate the magnetic properties of these materials. The molecular-based magnetism can be described as a model with layered honeycomb structure. The researches give an impetus to the theoretical investigation on the magnetic properties of an antifer-ro(ferri)-antiferro(ferri)magnetic Heisenberg system, which is illustrated in Fig. 1. The system is divided into two sublattices A and B with up and down spins, which are represented by small and big balls, respectively. In our previous work, magnetic behavior of ferro-anti-ferromagnetic Heisenberg system with a simple square structure has been investigated [4]. Here, we will apply the linear spin wave approximation and the retarded Green´s function to investigate the magnetic properties (including spin-wave spectra, magnon energy gap, magnetization and quantum fluctuation) of the antiferro(ferri)-antiferro(ferri)magnetic Heisenberg system on a honeycomb lattice.