The evolution of skyrmion crystals encapsulates skyrmion's critical behaviors, such as nucleation, deformation, and annihilation. Here, we achieve a tunable evolution of artificial skyrmion crystals in nanostructured synthetic antiferromagnet multilayers, which are composed of perpendicular magnetic multilayers and nanopatterned arrays of magnetic nanodots. The out-of-plane magnetization hysteresis loops and first-order reversal curves show that the nucleation and annihilation of the artificial skyrmion can be controlled by tuning the diameter of and spacing between the nanodots. Moreover, when the bottom layer thickness increases, the annihilation of skyrmion shifts from evolving into a ferromagnetic spin texture to evolving into an antiferromagnetic spin texture. Most significantly, nonvolatile multiple states are realized at zero magnetic field via controlling the proportion of the annihilated skyrmions in the skyrmion crystal. Our results demonstrate the tunability and flexibility of the artificial skyrmion platform, providing a promising route to achieve skyrmion-based multistate devices, such as neuromorphic spintronic devices.

中文翻译：

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合成反铁磁体中斯格明子晶体的纳米工程演化

skyrmion 晶体的演化封装了 skyrmion 的关键行为，例如成核、变形和湮灭。在这里，我们实现了纳米结构合成反铁磁多层中人工斯格明子晶体的可调演化，该多层由垂直磁性多层和磁性纳米点的纳米图案阵列组成。面外磁化磁滞回线和一阶反转曲线表明，人工斯格明子的成核和湮灭可以通过调整纳米点的直径和间距来控制。此外，当底层厚度增加时，斯格明子的湮灭从演变成铁磁自旋织构转变为演化为反铁磁自旋织构。最重要的是，通过控制斯格明子晶体中湮灭斯格明子的比例，在零磁场下实现非易失性多态。我们的结果证明了人工 skyrmion 平台的可调性和灵活性，为实现基于 skyrmion 的多态设备（例如神经形态自旋电子设备）提供了一条有前途的途径。