New type of hybrid nodal line semimetal in Be2Si
New type of hybrid nodal line semimetal in Be2Si
复制标题
Be2Si新型混合节线半金属
DOI：
10.1088/1367-2630/ab0d95
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发表时间：
2019
影响因子：
3.3
通讯作者：
Sun L. Z.
中科院分区：
文献类型：
--
作者：
Li Z. H.;Wang W.;Zhou P.;Ma Z. S.;Sun L. Z.
节线半金属是继Dirac和Weyl半金属之后的一种新型拓扑半金属，在现代凝聚态物理中引起了广泛的兴趣。最近，人们提出了一种混合节点线（Zhang et al 2018 Phys. Rev. B 97 125143），它主要来自各向异性相互作用。基于第一性原理计算和k·p模型，我们预测了具有拓扑非平凡电子态的立方Be 2Si在费米能级附近具有迷人的I型和II型混合节线.出乎意料的是，Be_2Si的低能电子态在kx和ky方向上是各向同性的，并为这种新型杂化节线的出现提出了一个新的有效模型。沿着r-K和r-X的高对称线的混合节线中的四重退化I型和II型节点受到镜面反射、时间反转和空间反转对称性的保护。自旋-轨道耦合效应仅在Be_2Si的混合节线中产生轻微的带隙，其非平凡性质仍然存在。此外，Be 2Si中的非平凡混合节线对外部应变是鲁棒的。结果表明，Be 2Si是未来研究非平凡拓扑半金属的理想材料，也是研究两类Dirac费米子相互作用的理想平台.
Following Dirac and Weyl semimetals, nodal line semimetals represent a new type of topological semimetal and attracted extensive interest in modern condensed matter physics. Recently, a kind of hybrid nodal lines have been proposed (Zhang et al 2018 Phys. Rev. B 97 125143) and it mainly come from anisotropy interaction. Based on the first-principle calculations and k·p model, we predict a cubic Be2Si with topological nontrivial electronic states exhibiting fascinating type-I and type-II hybrid nodal line around Fermi level. Unexpectedly the low energy electronic states of Be2Si are isotropy in kx and ky directions and a new effective model has been proposed for the appearance of this new type hybrid nodal line. The four-fold degenerated type-I and type-II nodal points in the hybrid nodal lines along the high symmetry lines of Γ–K and Γ–X are protected by mirror reflection, time reversal and space inversion symmetry. The spin–orbit coupling effect only induces slight band gap in the hybrid nodal lines in Be2Si whose nontrivial nature remains. Moreover, the nontrivial hybrid nodal lines in Be2Si are robust to external strain. The results in present work indicate that Be2Si are promising candidates for future experimental studies of nontrivial topological semimetals and an excellent platform to study the interaction between the two types Dirac fermions.