What is it about?
How to generate a high-contrast valley population of charge carriers is a fundamental goal of graphene valleytronics. In this work, we demonstrate that, a supperlattice structure can enhance both the valley-dependent resonant tunneling and transmission gap, resulting in a coexistence of insulating transmission gap of one valley and metallic resonant band of the other, hence a perfect valley filter that survives in a wide range of edge orientation, temperature, and structural parameters.
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Why is it important?
Before our work, a point contact with zigzag edges and breaking of the inversion symmetry have been proposed as a way for valley filter. However, these factors may break the specific bulk elementary excitation that is essential for most of the excitement about graphene. Our scheme achieve the goal in bulk graphene and the revealed perfect valley filter mechanism can be applied to any superlattice structures of a cell with valley filter effect.
Perspectives
The enhancement effect of resonant tunneling by periodic supperlattice structure is well know. I hope the enhancement effect of supperlattice on transmission gap revealed in the present work, which also plays an important role in quantum transport, can get more attention from researchers.
Dr. Yu Song
Read the Original
This page is a summary of: Generation of a fully valley-polarized current in bulk graphene, Applied Physics Letters, October 2013, American Institute of Physics,
DOI: 10.1063/1.4827995.
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