Department of Applied Physics, Center for NanoMaterials (cNM), Eindhoven University of Technology, Eindhoven, The Netherlands.
J Phys Condens Matter. 2012 Jan 18;24(2):024216. doi: 10.1088/0953-8984/24/2/024216. Epub 2011 Dec 15.
We theoretically and experimentally analyze the pinning of a magnetic domain wall (DW) at engineered anisotropy variations in Pt/Co/Pt strips with perpendicular magnetic anisotropy. An analytical model is derived showing that a step in the anisotropy acts as an energy barrier for the DW. Quantitative measurements are performed showing that the anisotropy can be controlled by focused ion beam irradiation with Ga ions. This tool is used to experimentally study the field-induced switching of nanostrips which are locally irradiated. The boundary of the irradiated area indeed acts as a pinning barrier for the domain wall and the pinning strength increases with the anisotropy difference. Varying the thickness of the Co layer provides an additional way to tune the anisotropy, and it is shown that a thinner Co layer gives a higher starting anisotropy thereby allowing tunable DW pinning in a wider range of fields. Finally, we demonstrate that not only the anisotropy itself, but also the width of the anisotropy barrier can be tuned on the length scale of the domain wall.
我们从理论和实验两方面分析了具有垂直磁各向异性的 Pt/Co/Pt 条状结构中各向异性工程变化对磁畴壁（DW）钉扎的影响。推导的解析模型表明，各向异性中的阶跃可以作为 DW 的能量势垒。通过使用 Ga 离子的聚焦离子束辐照进行定量测量，结果表明可以对各向异性进行控制。该工具用于对局部辐照的纳米条状结构进行场致开关的实验研究。辐照区域的边界实际上成为畴壁的钉扎势垒，并且钉扎强度随各向异性差异的增加而增加。改变 Co 层的厚度可以提供另一种调节各向异性的方法，结果表明，Co 层越薄，起始各向异性越高，从而可以在更宽的磁场范围内实现可调的 DW 钉扎。最后，我们证明不仅各向异性本身，而且各向异性势垒的宽度都可以在畴壁的长度尺度上进行调节。
