Non-Hermitian Moiré Valley Filter.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Valleytronics aims to utilize electron valley degrees of freedom for information processing.
• Implementing efficient valley filters, crucial for valleytronics, faces significant challenges.
• Graphene-based heterostructures are promising platforms for novel electronic functionalities.

Purpose of the Study:

• To propose and theoretically investigate a novel valley filter based on a graphene bilayer.
• To demonstrate the generation of a valley-polarized current using engineered moiré patterns and heterostrain.
• To explore the underlying physics, including non-Hermitian effects, and assess the filter's robustness and tunability.

Main Methods:

• Theoretical modeling of a graphene bilayer with a 1D moiré pattern induced by heterostrain.
• Development of an effective non-Hermitian theory to describe valley-dependent electron dissipation.
• Analysis of valley-resolved non-Hermitian skin effect for current generation.

Main Results:

• Achieved nearly 100% valley polarization over a broad parameter range.
• Demonstrated electrical tunability of the valley filter's functionality.
• Showcased high tolerance to imperfections like disorder and edge defects due to a non-Hermitian topological scenario.

Conclusions:

• The proposed graphene bilayer structure serves as an efficient and robust valley filter.
• The device leverages valley asymmetric interlayer coupling and non-Hermitian physics.
• This work provides a promising pathway for practical valleytronics devices with relaxed fabrication constraints.