Self-consistent mean-field theory to anisotropic ferrimagnetic chain with bond alternation

Abstract

We investigate the finite temperature properties of anisotropic ferrimagnetic chain with bond alternation. The spin excitation spectrum as well as the thermodynamic quantities are calculated by means of the extended self-consistent mean-field theory. Two branches of energy spectrum are obtained and the energy gap between them is 1.7641 at zero temperature which agrees quite well with other numerical results. The contribution of bonding alternation δ, anisotropy λ and magnetic field H to the energy gap are present in this research. The other thermodynamic quantities varying with δ and λ, such as ground state energy e, free energy f, specific heat cm, magnetization m and uniform magnetic susceptibility Tχuni/Ng2 are explicitly discussed, respectively. At Heisenberg point, the e0 is -0.7326 and f0 is -1.4659 at zero temperature in this work are reasonable compared with the results calculated by other methods. The effect of λ and δ on the thermodynamic quantities at finite temperature are also well consistent with other established methods.