A Non-Hermitian Moiré Valley Filter

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 moiré 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.

6 pages, 3 figures

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Cited by in corpus (14)

• Quantum entanglement and non-Hermiticity in free-fermion systems
• Quantum-Classical Correspondence of Non-Hermitian Symmetry Breaking
• Tunneling valley Hall effect induced by coherent geometric phase
• Non-Hermitian superconducting diode effect
• Nonlinear Hall effects with an exceptional ring
• Fidelity and criticality in the nonreciprocal Aubry-Andr{é}-Harper model
• Non-Hermitian Delocalization Induced by Residue Imaginary Velocity
• Exceptional topology in non-Hermitian twisted bilayer graphene
• Valley Gapless Semiconductor: Models and Applications
• Non-Hermitian higher-order topological insulators enabled by altermagnet engineering
• Nodal Spectral Functions Stabilized by Non-Hermitian Topology of Quasiparticles
• Nonreciprocal ballistic transport in multi-layer Weyl semimetal films with surface engineering
• 1D Spontaneous Symmetry Breaking in thermal equilibrium via Non-Hermitian Construction
• Beyond characteristic equations: A unified one-dimensional non-Bloch band theory via wavefunction data