论文标题
在几何不对称双层结构中具有非磁性双层的非偏位集体磁波模式
Nonreciprocal collective magnetostatic wave modes in geometrically asymmetric bilayer structure with nonmagnetic spacer
论文作者
论文摘要
非肾脏的振动波和频率在相反方向传播的振幅和频率的不等性，是前瞻性镁质设备中的关键特性。在这里，我们在实验和理论上证明了一种简单的方法，可以通过其几何不对称的磁耦合铁磁双层结构诱导磁性非磁性双层结构。使用Brillouin Light散射，我们显示了Fe $ _ {81} $ ga $ _ {19} $/cu/cu/fe $ _ {81} $ ga $ _ $ _ {19} $结构的两个集体自旋波模式的形成。声学和光学集体旋转波模式的分散体的实验重建和理论建模表明，两者的非股骨能力达到了几个百分之几的波数，$ 22〜 \ cdot〜10^4 $ rad cm $^{ - 1} $。分析表明，由于旋转波频率对层厚度的明显依赖性，反向传播耦合模式向任何层的幅度的振幅朝向任何层。所提出的方法可以设计具有宏伟逻辑门的给定自旋波分散的多层铁磁结构。
Nonreciprocity, i.e. inequivalence in amplitudes and frequencies of spin waves propagating in opposite directions, is a key property underlying functionality in prospective magnonic devices. Here we demonstrate experimentally and theoretically a simple approach to induce frequency nonreciprocity in a magnetostatically coupled ferromagnetic bilayer structure with a nonmagnetic spacer by its geometrical asymmetry. Using Brillouin light scattering, we show the formation of two collective spin wave modes in Fe$_{81}$Ga$_{19}$/Cu/Fe$_{81}$Ga$_{19}$ structure with different thicknesses of ferromagnetic layers. Experimental reconstruction and theoretical modeling of the dispersions of acoustic and optical collective spin wave modes reveal that both possess nonreciprocity reaching several percent at the wavenumber of $22~\cdot~10^4$ rad cm$^{-1}$. The analysis demonstrates that the shift of the amplitudes of counter-propagating coupled modes towards either of the layers is responsible for the nonreciprocity because of the pronounced dependence of spin wave frequency on the layers thickness. The proposed approach enables the design of multilayered ferromagnetic structures with a given spin wave dispersion for magnonic logic gates.
