二维嵌套复式三角晶格磁振子晶体的带隙结构

Calculations on the Band Structure of Two-dimensional Triangular Magnonic Crystals with Nesting Complex Lattice

首先构造了二维嵌套复式三角晶格的磁振子晶体模型,其散射体由2个相切的大小相同的铁磁材料圆柱体构成,它们按照一定晶格常数三角排列在另一种铁磁材料基底中;其次,发展了可用于数值计算研究自旋波在嵌套复式三角晶格磁振子晶体中本征性质的平面波展开法.以2个相切的铁圆柱代替原来简单三角晶格中的1个铁圆柱,再以三角点阵排列在氧化铕基底材料中构成的二维嵌套复式三角晶格磁振子晶体为研究对象,通过数值计算自旋波在其中的带结构,研究了带隙宽随体积填充的变化行为,并与简单三角晶格的带隙结构进行比较.结果表明,嵌套复式三角晶格的磁振子晶体可以在更低的体积填充率下产生带隙,并且能够在更高频的情况下产生较宽的带隙,从而达到带隙优化的目的,为实现自旋波的可控操作提供了一种方案.

Firstly,a model of two-dimensional triangular magnonic crystals with nesting complex lattice is proposed,in which the scatterers are composed of two tangential ferromagnetic material cylinders with the same size,arranged in another ferromagnetic material matix according to a certain lattice constant.The plane-wave expansion method is developed,and this method can be used to numerically investigate the eigen-properties of spin waves in magnonic crystals with nesting complex triangle lattices.Taking the twodimensional magnonic crystal with nesting complex triangle lattice consisting of two tangential Fe rods in place of single Fe rod in the simple triangle lattice with EuO matrix material for an example,spin-wave band structures are numerically calculated and the behaviour of the gap changing as the filling fraction of volume are compared with that of the simple triangle lattice.The results show that the spin-wave gaps can be generated in nesting complex triangle lattice magnonic crystals with the lower volume filling ratio and the higher frequency than those of simple magnonic crystals with triangle lattice.The optimization of the band gap can be achieved,and an approach of the controllable spin waves has been proposed.