The Elementary Excitation And Properties Of The Ferrimagnetic Diamond Chain System

The elementary excitations spectrums in the system of a spin-1/2one-dimensional ferrimagnetic diamond chain at low temperature were calculated byJordan-Wigner transformations and invariant eigen-operator method. And threenon-degenerate elementary excitations spectrums were obtained. The Hamiltonian ofthe system was decoupled with invariant eigen-operator method, the decouplingprocess was convenient than conventional unitary transformation method. And it wasautomatically decoupled directly from self-representation of the system, thus it wasvery convenient to calculate partition function of the system. And the advantages ordeficiencies of invariant eigen-operator method was discussed in this paper. Theelementary excitations spectra in the system of a spin-1/2Heisenberg ferrimagneticdiamond chain at low temperature were calculated by Jordan-Wigner transformationsand invariant eigen-operator method. And three non-degenerate elementaryexcitations spectra were obtained. The Hamiltonian of the system was diagonalizedwith invariant eigen-operator method, and the partition function and magnetization ofthe system at finite temperature and external magnetic field were derived as well. Byanalyzing the changing rule of every exchange integral (J1, J2, J3, Jm) to magnetization ofthe system with external magnetic field at absolute zero and finite temperature, three criticalmagnetic field intensities (HCB, HCE, HCS) of the system were obtained, explaining theorigin of three critical magnetic field intensities and the occurrence of1/3magnetization plateau when magnetization of the system changing with externalmagnetic field from the property of three elementary excitations.