【作者】 许忻平；

【导师】 梁九卿；

【作者基本信息】 山西大学 ， 理论物理， 2003， 硕士

【摘要】 本文的主要目的是将1+1维非线性场的静态瞬子理论推广到2+1维。为此选取了被广泛研究的Φ~4和sine-Gordon场模型作为讨论对象。文章首先回顾了1+1维Φ~4和sine-Gordon场方程静态瞬子的相关理论，讨论了静态瞬子的能量密度、及其稳定性。进而，用类似的方法研究了2+1维Φ~4场模型的静态瞬子组态及其稳定性。最后考虑由双轴各向异性分子磁体形成的理想无界膜，在强各向异性极限下，采用半经典近似方法，将磁化矢量的时空运动方程约化为2+1维sine-Gordon场方程，从而得到各类畴结构。我们发现静态周期瞬子正是铁磁膜中的畴壁，用相应的瞬子理论讨论了畴壁的稳定性。更多还原

【Abstract】 It is our main purpose to extend the static instantons of scalar 4 - andsine-Gordon-theory of 1+1 dimension to that of 2+1 dimension . First, we give a brief review of instanton theory of 1+1 dimension .Then we obtain the instantons in 4 -field model of 2+1 dimension . In the last part of the paper, we derive theEuclidean equation of motion of the magnetic vector in a theoretical magnetic film consisting of biaxial-anisotropic molecular ferromagnets ,which is reduced to the 2+1 dimensional sine-Gordon field equation in the strong anisotropy limit .We obtain various domain structures which are the static solutions of the sine-Gordon field equation. In particular, it is found that static instantons are just domain wall solutions in the magnetic film. Stability of the domain walls is also investigated in terms of the instanton theory.更多还原