The Spin-waves And Specific Heat In Zig-zag Spin Ladder Model

Recently low-dimensional quantum spin system is one of the most activeareas of research in condensed matter physics. There is a significant researchinterest especially in one-dimensional and quasi-one-dimensional systems. Themost well-known model of interacting spins is Heisenberg model. Such systemsexhibit a vatiety of phenomena on the low-temperature condition. In 1931,the Bathe Ansatz(BA) was formulated by Bathe. The exact solution of one-dimensional Heisenberg model can be obtained with the help of the BA tech-nique. But in general, the resulting model is no longer integrable and one hasto resort to approximate methods together with numerical calculations. Withthe help of those methods, many profound results were reported by the study-ing of Heisenberg model. However, the physical properties of one-dimensionalXXZ Heisenberg spin chain model in an external magnetic field and spin laddermodels are still worth discussing.By means of Jordan-Wigner transformation and Green's function method,we obtain the spin-waves, sublattice magnetic moments, internal energy andspecific heat for XXZ spin chain model in an external magnetic field. We findthe spin-waves have a linear dependence on the external magnetic field, andsublattice magnetic moments and specific heat are exponential functions oftemperature and the external magnetic field.Besides one-dimensional XXZ Heisenberg spin chain system, In this paper,we also discuss the spin-waves, sublattice magnetic moments, internal energy and specific heat in zig-zag spin ladder model with frustration. The results weobtained can give some references for the solutions of more complex frustratedquantum spin systems.