Layer-dependent zero-line modes in antiferromagnetic topological insulators

Abstract

Recently, the magnetic domain walls have been experimentally observed in antiferromagnetic topological insulators MnBi 2 Te 4 . Here we study the intrinsic topological zero-line modes (ZLMs) that appear along the domain walls, and find that these ZLMs are layer dependent in MnBi 2 Te 4 multilayers. We reveal the role of the spatial layer degree of freedom and magnetic domain wall configurations in determining the electronic transport properties and the distribution of the ZLMs in antiferromagnetic topological insulator systems. For antiferromagnetic domain wall with out-of-plane magnetization within each domain, we find that ZLMs are only distributed in the odd-number layers equally. For the Néel domain wall, the ZLMs are no longer distributed in the odd-number layers equally due to the mirror symmetry (M z ) breaking, and can exist in the even-number layers in multilayer systems. Moreover, the ZLMs are mainly distributed in the outermost layers with increasing layer thickness. Our findings lay out a strategy in manipulating ZLMs and can be utilized to distinguish the corresponding magnetic structures.

Two-dimensional Dirac fermions in a mass superlattice

“…We expect that our results will also be relevant in this platform. Theoretical predictions for layer-dependent zero-line modes in antiferromagnetic topological insulator multilayer structures based on MnBi 2 Te 4 [56] suggest that our theory can also be applied in that context. An important caveat when comparing our results to experiments concerns the idealized step-like mass term considered here.…”

Fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters utilizing zero-line modes in a three-terminal device

“…It has been found that graphene-like materials can exhibit abundant topological phases under different external fields applied to the whole system, [11][12][13][14][15] and the side potential applied to the boundary of the system is also crucial for generating and manipulating topological phases and corresponding edge states. [16,17] In particular, a large number of zero-line modes (ZLMs) [18][19][20] that can arise from the interface separating different topological phases have been found in addition to outer edge states [11,[21][22][23] induced at the interface between topological phases and the topologically trivial vacuum. In particular, ZLMs are related not only to the Chern numbers but also to the valley Chern numbers, which are also known as kink states and inner edge states, respectively.…”