标题： 截断星形纳米磁体中反涡旋核心的自旋扭矩驱动非均匀动力学 显示英文标题

标题： Spin-Torque-Driven Non-uniform Dynamics of an Antivortex Core in Truncated Astroid Shaped Nanomagnets

摘要： 由于磁偶极相互作用的主导效应，在微/纳米尺度上图案化的自旋织构可以在连续磁性薄膜畴结构中稳定下来。 制造这类器件能够全面研究由高度集中的自旋极化/纯自旋电流激发的射频动力学。 为此，在本研究中，我们采用截断的星形几何形状以实现稳定的磁反涡核成核/湮灭，这种成核/湮灭在各种温度下可以通过各向异性磁阻（AMR）检测到。 此外，通过沉积一层20纳米厚的坡莫合金软磁薄膜，并覆盖一层2纳米厚的重金属铂层，我们能够探测由半反涡核核心引起的自旋轨道力矩诱导激发，这些半反涡核核心类似于孤立的反涡核，产生具有高Q值（~50000）的GHz频率振荡。 观察到的射频振荡可以归因于微磁模拟中靠近稳定反涡核成核位点的非均匀畴壁振荡模式。 对反涡核对自旋电流响应的基本研究对于评估其在高频自旋电子器件（如存储器计算机）中的潜在应用至关重要。 显示英文摘要

摘要： Spin textures that are not readily available in the domain structures of continuous magnetic thin films can be stabilized when patterned to micro/nano scales due to the dominant effect of dipolar magnetic interactions. Fabrication of such devices enables a thorough study of their RF dynamics excited by highly concentrated spin-polarized/pure-spin currents. For this purpose, in this study, we have employed a truncated astroid geometry to achieve stable magnetic antivortex core nucleation/annihilation which was detectable using the anisotropic magnetoresistance (AMR) at various temperatures. Furthermore, by depositing a soft magnetic thin film (20 nm thick permalloy) capped with a heavy-metal 2nm Pt layer, we were able to probe the spin orbit torque induced excitations accompanied by self-torque due to half-antivortex cores reminiscent of an isolated-antivortex, yielding GHz frequency oscillations with high quality factors (~50000). The observed RF oscillations can be attributed to a non-uniform domain wall oscillation mode close to the stable-antivortex core nucleation site as seen in micromagnetic simulations. This fundamental study of antivortex core response to spin currents is crucial for the assessment of their potential applications in high frequency spintronic devices such as reservoir computers.