Liu Xue, Yue Chunlei, Erohin Sergey V, Zhu Yanglin, Joshy Abin, Liu Jinyu, Sanchez Ana M, Graf David, Sorokin Pavel B, Mao Zhiqiang, Hu Jin, Wei Jiang
Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China.
Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, United States.
Nano Lett. 2021 Jun 9;21(11):4887-4893. doi: 10.1021/acs.nanolett.0c04946. Epub 2021 Apr 9.
In a topological semimetal with Dirac or Weyl points, the bulk-boundary correspondence principle predicts a gapless edge mode if the essential symmetry is still preserved at the surface. The detection of such topological surface state has been considered as the fingerprint prove for crystals with nontrivial topological bulk band. On the contrary, it has been proposed that even with symmetry broken at the surface, a new surface band can emerge in nonsymmorphic topological semimetals. The symmetry reduction at the surface lifts the bulk band degeneracies and produces an unusual "floating" surface band with trivial topology. Here, we first report quantum transport probing to ZrSiSe thin flakes and directly reveal transport signatures of this new surface state. Remarkably, though topologically trivial, such a surface band exhibits substantial two-dimensional Shubnikov-de Haas quantum oscillations with high mobility, which signifies a new protection mechanism and may open applications for quantum computing and spintronic devices.
在具有狄拉克点或外尔点的拓扑半金属中，体态 - 边界对应原理预测，如果表面仍保留基本对称性，则会存在无隙边缘模式。这种拓扑表面态的检测被视为具有非平凡拓扑体态能带的晶体的指纹证明。相反，有人提出，即使表面对称性被破坏，在非对称拓扑半金属中也会出现新的表面能带。表面对称性的降低消除了体态能带的简并性，并产生了具有平凡拓扑的异常“浮动”表面能带。在此，我们首次报道了对ZrSiSe薄片的量子输运探测，并直接揭示了这种新表面态的输运特征。值得注意的是，尽管这种表面能带在拓扑上是平凡的，但它表现出具有高迁移率的大量二维舒布尼科夫 - 德哈斯量子振荡，这意味着一种新的保护机制，可能为量子计算和自旋电子器件开辟应用前景。
