We study the magnetic anisotropy of multilayer nanostructures [Co–Al${}_2$O${}_3$]${}_N$ with fixed Co island layer thickness ($d\approx 1.2\mathrm{nm}$) and varying Al${}_2$O${}_3$ layer thickness. We use the Kerr effect to measure the magnetization hysteresis loops at different orientations of the magnetic field. We observed a unidirectional magnetic anisotropy in structures with small thicknesses of Al${}_2$O${}_3$ layers ($d<1.4\mathrm{nm}$) when the exchange interaction between the Co layers is large. This anisotropy was oriented at 150° with respect to the easy axis of a continuous Co film. We believe that the unidirectional anisotropy can be caused by the super-vortex magnetization of the multilayer structure, while the unidirectional magnetization is caused by the projection of the super-vortex core on the sample plane.

我们研究了多层纳米结构的磁各向异性 [Co-Al${}_2$哦${}_3$]${}_N$ 具有固定 Co 岛层厚度 ($d\approx 1.2\mathrm{纳米}$) 和变化的铝${}_2$哦${}_3$层厚。我们使用克尔效应来测量不同磁场方向的磁化磁滞回线。我们在具有小厚度 Al 的结构中观察到单向磁各向异性${}_2$哦${}_3$ 层（$d<1.4\mathrm{纳米}$) 当 Co 层之间的交换相互作用很大时。这种各向异性相对于连续 Co 膜的易轴以 150° 取向。我们认为单向各向异性可能是由多层结构的超涡旋磁化引起的，而单向磁化是由超涡旋核在样品平面上的投影引起的。