掺杂二维Ising系统的相图研究

用Monte-Carlo模拟方法研究了非磁性掺杂下二维Ising系统的相图.在平面四角点阵上,以晶格Ising模型为框架,在周期性边界条件下详细观测了不同非磁性物质掺杂浓度下系统磁化强度和磁畴生长随温度变化的关系,并根据有限尺寸标度理论得到其相变温度.结果发现:当掺杂浓度较低时,存在铁磁与顺磁间的相变;而掺杂浓度较高时,在仅考虑近邻作用下系统无铁磁相.当考虑次近邻相互作用时,发现相变温度将升高.另外考察了不同掺杂浓度下的自旋密度关联.

Investigation on the phase diagram of the two-dimensional doped Ising model

The phase diagram of two-dimensional doped Ising model with nonmagnetic matter is studied by Monte-Carlo method in this paper.Under different doping concentration,the relation between sys- tem magnetization/domain boundary growth and temperature increasing is observed under periodic boundary condition on the plane square lattices,and the phase transition temperature is also obtained with finite scale measure theory.The result shows that there exists phase transition from ferromagnetic state to paramagnetic state when doping concentration is low,and when doping concentration is high, only nearest-neighbor interaction considered,there is no ferromagnetic state.When next-nearest-neigh- bor interaction is considered,it is found that phase transition temperature is increased.In this paper,the spin density relating of different doping concentration is also studied.