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arXiv · 2310.10973

A Non-Hermitian Moir\'{e} Valley Filter

Kai Shao·Hao Geng·Erfu Liu·Jose L. Lado·Wei Chen·D. Y. Xing
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Abstract

A valley filter capable of generating a valley-polarized current is a crucial element in valleytronics, yet its implementation remains challenging. Here, we propose a valley filter made of a graphene bilayer which exhibits a 1D moir\'{e} pattern in the overlapping region of the two layers controlled by heterostrain. In the presence of a lattice modulation between layers, electrons propagating in one layer can have valley-dependent dissipation due to valley asymmetric interlayer coupling, thus giving rise to a valley-polarized current. Such a process can be described by an effective non-Hermitian theory, in which the valley filter is driven by a valley-resolved non-Hermitian skin effect. Nearly 100\% valley-polarization can be achieved within a wide parameter range and the functionality of the valley filter is electrically tunable. The non-Hermitian topological scenario of the valley filter ensures high tolerance against imperfections such as disorder and edge defects. Our work opens a new route for efficient and robust valley filters while significantly relaxing the stringent implementation requirements.

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Kai Shao, Hao Geng, Erfu Liu, Jose L. Lado, Wei Chen, D. Y. Xing. 2023-10-17. A Non-Hermitian Moir\'{e} Valley Filter. https://doi.org/10.1103/physrevlett.132.156301

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