We study theoretically the electronic structure of topological nodal-line semimetals. We show that, in the presence of a gap-opening spatially dependent mass term that forms a domain wall, an in-gap charged localized mode emerges at the domain wall. It turns out that such a domain wall is realized by head-to-head (or tail-to-tail) bulk electric polarizations. The dispersion of the localized mode evolves from gapless to gapped as the bulk bandgap increases, which means that its conductivity is tunable. The localized mode has a topological origin, i.e., a topological confinement is realized, which is understood by a semiclassical topological number defined in semiclassical momentum-real space. In contrast to previous studies, the origin of the charged domain wall in this study is purely electronic, i.e., due to the band topology. Moreover, this study demonstrates a topological confinement at the interface between two insulators without bulk topological numbers. We discuss a possible experimental realization of the stable, electrically-tunable charged domain wall.

中文翻译：

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节点线半金属中的拓扑限制可调整的带电畴壁

我们从理论上研究拓扑结线半金属的电子结构。我们表明，在存在形成畴壁的空位开放空间相关质量项的情况下，在畴壁处出现带隙内带电局部化模式。事实证明，这种畴壁是通过头对头（或尾对尾）体电极化实现的。随着体带隙的增加，局域模的色散从无间隙演变为带隙，这意味着其电导率可调。局部化模式具有拓扑起源，即，实现了拓扑限制，这可以通过在半经典动量-实际空间中定义的半经典拓扑数来理解。与以前的研究相反，本研究中带电畴壁的起源是纯电子的，即由于带拓扑。此外，这项研究表明在两个绝缘子之间的界面上存在拓扑限制，而没有整体拓扑数。我们讨论了稳定的，电可调的带电畴壁的可能的实验实现。