Indirect magnetic interaction mediated by Fermi arc and boundary reflection near Weyl semimetal surface
Indirect magnetic interaction mediated by Fermi arc and boundary reflection near Weyl semimetal surface
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DOI：
10.1088/1367-2630/aae3f9
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发表时间：
2018-10
影响因子：
3.3
通讯作者：
Hou-Jian Duan;S. Zheng;Pei-Hao Fu;Rui-Qiang Wang;Junfeng Liu;Guang-Hui Wang;Mou-Shu Yang
中科院分区：
文献类型：
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作者：
Hou-Jian Duan;S. Zheng;Pei-Hao Fu;Rui-Qiang Wang;Junfeng Liu;Guang-Hui Wang;Mou-Shu Yang
我们从理论上研究了分布在外尔半金属表面附近的磁性杂质之间的 Ruderman-Kittel-Kasuya-Yosida (RKKY) 相互作用。与之前的研究相反，我们进一步考虑了费米弧和体态相互作用以及界面反射的影响。结果表明，RKKY 图案明显受到费米弧表面态以及界面反射的调节。费米弧表面态通过干扰体态来介导 RKKY 相互作用。由此产生的短程杂质距离 R 中的干扰贡献在大小上与体带贡献相当，甚至在表面附近主导了后者。它会增强或减弱体积贡献，具体取决于杂质和费米能量的相对方向。更重要的是，对于长程杂质距离，干扰项占主导地位，因为它可以将衰减率从原始体 R−5 定律延长到有限（零）费米能量的 R−2 (R−3)。界面反射不仅增强了 RKKY 相互作用的幅度，并将其各向异性从原来的 XXZ 改变为 XYZ 或 Ising 自旋模型，而且还生成平行于连接 Weyl 节点的线的额外扭曲 RKKY 项，这是没有界面效应的场景中所缺少的。它们源自杂质与其他杂质的镜像之间的相互作用。我们进一步详细分析衰减率和跳动模式的空间各向异性。这些发现提供了对外尔费米子介导的表面磁相互作用的更深入的了解。
We theoretically investigate the Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction between magnetic impurities distributed in the vicinity of the surface of a Weyl semimetal. Contrary to previous studies, we further take into account the influence of interplay of the Fermi arc and bulk states, and interface refection. It is shown that the RKKY pattern is significantly mediated by the Fermi-arc surface state along with the interface reflection. The Fermi-arc surface state mediates the RKKY interaction by interfering with the bulk states. The resulting interference contribution in the short-range impurity distance R is comparable in magnitude to the bulk-band contribution and even dominates the latter near the surface. It either enhances or weakens the bulk contribution, depending on the relative orientation of impurities and Fermi energy. More importantly, for the long-range impurity distance the interference term dominates in that it can prolong the decay rate from the original bulk R−5-law to R−2 (R−3) for finite (zero) Fermi energy. The interface reflection not only enhances the magnitude of the RKKY interaction and changes its anisotropy from the original XXZ to XYZ or Ising spin model, but also generates extra twisted RKKY terms parallel to the line connecting Weyl nodes, lacked in the scenario without the interface effect. They originate from the interaction between the impurity and the mirror image of the other impurity. We further analyze in detail the spatial anisotropy of the decay rate and beating pattern. These findings provide a deeper insight into surface magnetic interaction mediated by Weyl fermions.