Tilted graphene junctions for valleytronics applications

Valleytronics is one of the disruptive technologies, being explored for quantum computing. Valley qubits are more robust to external environmental perturbations compared to conventional charge-based qubits. In order to develop valleytronic devices, achieving valley polarization is paramount. Various 2D materials have been widely explored for realizing valley-based devices because of their unique band structure. Most of these proposed works used the scattering mechanism with line defects, strain barriers, and magnetic barriers. However, they are limited by low transmission values and changes in polarization directionality. In order to overcome these issues, we propose an electrostatically tuned valley polarizer device that incorporates a simple tilted graphene PN junction. The tilted interface scatters Fermions anisotropically based on the valley index. The device variables like tilt angle, junction transition width, position, and electron energy determine polarization. We performed numerical simulations using the scattering matrix approach for analyzing the underlying physics and summarized the optimal conditions for achieving maximum polarization.