Spin-resolved inelastic electron scattering by spin waves in noncollinear magnets
Spin-resolved inelastic electron scattering by spin waves in noncollinear magnets
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DOI：
10.1103/physrevb.97.024431
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发表时间：
2018-01-26
影响因子：
3.7
通讯作者：
Lounis, Samir
中科院分区：
文献类型：
--
作者：
dos Santos, Flaviano Jose;Dias, Manuel dos Santos;Lounis, Samir
物质的拓扑非共线磁相是未来信息纳米技术的许多建议的核心，具有基于纳米薄膜和纳米线的新器件概念。它们的运作需要理解和控制潜在的动力学，包括自旋波等激发。到目前为止，还没有实验技术试图探测非共线低维系统中的大波矢自旋波。本文解释了电子弹性散射是如何探测非共线磁体的集体自旋激发谱的，它适用于表面和薄膜的研究。为了揭示这种非共线样品中自旋波的特殊性，我们建议使用自旋极化电子能量损失谱与自旋分析仪增强。利用自旋分析仪检测散射电子的极化，定义了四个自旋相关的散射通道，这使得我们能够过滤和选择特定的自旋波模式。我们以拓扑非平凡的skyrmion晶格，自旋螺旋相，和传统的铁磁体为例。然后，我们证明，反直觉和铁磁的情况下，即使是非自旋翻转过程可以产生自旋波在非共线基板。测量的分散和寿命的激发模式允许我们指纹的磁性基板。
Topological noncollinear magnetic phases of matter are at the heart of many proposals for future information nanotechnology, with novel device concepts based on ultrathin films and nanowires. Their operation requires understanding and control of the underlying dynamics, including excitations such as spin waves. So far, no experimental technique has attempted to probe large wave-vector spin waves in noncollinear low-dimensional systems. In this paper, we explain howinelastic electron scattering, being suitable for investigations of surfaces and thin films, can detect the collective spin-excitation spectra of noncollinear magnets. To reveal the particularities of spin waves in such noncollinear samples, we propose the usage of spin-polarized electron-energy-loss spectroscopy augmented with a spin analyzer. With the spin analyzer detecting the polarization of the scattered electrons, four spin-dependent scattering channels are defined, which allow us to filter and select specific spin-wave modes. We take as examples a topological nontrivial skyrmion lattice, a spin-spiral phase, and the conventional ferromagnet. Then we demonstrate that, counterintuitively and in contrast to the ferromagnetic case, even non-spin-flip processes can generate spin waves in noncollinear substrates. The measured dispersion and lifetime of the excitation modes permit us to fingerprint the magnetic nature of the substrate.