Valley-dependent Quantum Transportation through Barriers in Bilayer Graphene along Armchair Direction

Yen-Ju Lin^1*, Bing-Chen Huang¹, Feng-Wu Chen², Yu-Shu G. Wu^1,2

¹Department of Electrical Engineering, National Tsing-Hua University, Hsin-Chu, Taiwan
²Department of Physics, National Tsing-Hua University, Hsin-Chu, Taiwan

* Presenter:Yen-Ju Lin, email:s105063807@m105.nthu.edu.tw

The unique degree of freedom in 2D hexagonal materials – valley pseudospin provides a viable solution for signal processing with low energy consumption, with the two key mechanisms – trigonal warping and valley orbit interaction available for valley pseudospin manipulation. In our work, we develop a model for valley transport in AB-stacked bulk graphene along the armchair direction. Based on a tight binding description, we study the valley polarization in electron current transmitted through quantum structures, with the structure formed of a step potential, a single quantum barrier or double barriers. The result shows that a high valley contrast can be induced in the low transmission regime, in the case of a one-barrier structure. On the other hand, a double barrier structure manifests a high valley polarization near transmission resonance, with promising applications for the generation of valley polarized electron sources.

Keywords: Graphene, Valleytronics, Valley filter