[online] Topological valleytronics in bilayer graphene

10/01/2021 - 3:30pm to 4:30pm
Speaker(s) / Presenter(s): 
Jun Zhu (Penn State)
Type of Event (for grouping events):

The valley pseudospin of 2D hexagonal lattices offers a new electronic degree of freedom to explore many-body ground states and novel paradigms of electronic applications. It is analogous to electron spin however coupling to an electric field offers a powerful control knob that is nimble and application friendly. In this talk, I will describe how we create valley-momentum locked topological 1D channels in Bernal stacked bilayer graphene by electrically generating inverted band structures. This all-electric construction gives us the ability to realize reconfigurable ballistic waveguides and device operations that explicitly explore the valley-momentum locking of the 1D channels. I will show the working of a topological valley valve, which does not require valley-polarized current to operate but relies on the control of topology, and a continuously tunable electron beam splitter that is analogous to the function of a quantum point contact. The realization of these devices requires the development of high-precision lithography on high-quality BN/graphene/BN heterostructures. Time permitting I will touch upon recent development in our lab where new interaction-driven ground states emerge from exploring the valley pseudospin degrees of freedom in the fractional quantum Hall regime. 

Host: Murthy

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