具有Dzyaloshinskii-Moriya作用和晶体场作用的Heisenberg模型的临界性质

利用平均场近似的方法,研究了具有Dzyaloshinskii-Moriya(DM)作用和纵向晶体场作用的自旋S=1的Heisenberg 模型的临界性质,得到了该系统的相图.研究结果表明:所研究系统存在三临界点,并且约化晶体场作用参量和约化 DM作用参量分别连续变化时,系统的三临界温度不随相应参量单调变化,约化三临界温度分别存在一个最小值.系统的这种临界性质可以解释为系统的交换耦合作用、晶体场作用DM作用之间相互竞争的结果.

The Critical Properties of the Heisenberg Model with the Dzyaloshinskii-Moriya and Crystal Field Interactions

Using the mean-field method,the Heisenberg model with the Dzyaloshinskii-Moriya(DM) and crystal field interactions has been studied.The phase diagrams of this system are obtained,and it is found that the system exhibits the tricritical point.When the reduced DM interaction parameter and the reduced crystal field interaction parameter change separately and continuously,the tricritical temperature doesn’t monotonously change,and has a minimum.The critical properties of the system may be interpreted as a result of a competition among the exchange interaction,the crystal field interaction and the DM interaction.