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Condensed Matter > Mesoscale and Nanoscale Physics
Title: A Non-Hermitian Moiré Valley Filter
(Submitted on 17 Oct 2023 (v1), last revised 18 Apr 2024 (this version, v2))
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.
Submission history
From: Kai Shao [view email][v1] Tue, 17 Oct 2023 03:37:46 GMT (1639kb,D)
[v2] Thu, 18 Apr 2024 06:35:58 GMT (1634kb,D)
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