Fully Spin-Polarized Nodal Loop Semimetals in Alkaline Metal Monochalcogenide Monolayers.
Fully Spin-Polarized Nodal Loop Semimetals in Alkaline Metal Monochalcogenide Monolayers.
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DOI：
10.1021/acs.jpclett.9b00906
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发表时间：
2019-03
期刊：
影响因子：
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通讯作者：
Xiaodong Zhou;Run-Wu Zhang;Zeying Zhang;Da-Shuai Ma;W. Feng;Y. Mokrousov;Yugui Yao
中科院分区：
文献类型：
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作者：
Xiaodong Zhou;Run-Wu Zhang;Zeying Zhang;Da-Shuai Ma;W. Feng;Y. Mokrousov;Yugui Yao
铁磁材料中的拓扑半金属由于在自旋电子学中的潜在应用而引起了广泛的关注。利用第一性原理密度泛函理论和有效的晶格模型，我们提出了一类新的拓扑半金属，在碱金属单硫属化物 MX（M = Li、Na、K、Rb 或 Cs；X = S、Se 或 Te）单层中具有完全自旋极化的节点环。半金属铁磁性可以在MX单层中建立，其中在费米能处发现由具有相同自旋分量的两个交叉能带形成的一个节点环。即使考虑自旋轨道耦合，由于 Mz 镜面提供的对称保护，这种节点环半金属仍然存在。该体系中的量子反常霍尔态和类Weyl半金属也可以通过将自旋从面外方向旋转到面内方向来实现。因此，MX 单层具有丰富的拓扑相，为实现先进的自旋电子概念提供了一个出色的平台。
Topological semimetals in ferromagnetic materials have attracted an enormous amount of attention due to potential applications in spintronics. Using first-principles density functional theory together with an effective lattice model, here we present a new family of topological semimetals with a fully spin-polarized nodal loop in alkaline metal monochalcogenide MX (M = Li, Na, K, Rb, or Cs; X = S, Se, or Te) monolayers. The half-metallic ferromagnetism can be established in MX monolayers, in which one nodal loop formed by two crossing bands with the same spin components is found at the Fermi energy. This nodal loop half-metal survives even when considering the spin-orbit coupling owing to the symmetry protection provided by the Mz mirror plane. The quantum anomalous Hall state and Weyl-like semimetal in this system can be also achieved by rotating the spin from the out-of-plane to the in-plane direction. The MX monolayers hosting rich topological phases thus offer an excellent platform for realizing advanced spintronic concepts.