Jun Zhu (Penn State)
Thu. August 31st, 2017, 4:00 pm-5:00 pm
Quantum valley Hall kink states and valleytronics in bilayer graphene
Conventional field effect transistors control current transmission by controlling the charge of carriers. The advent of two-dimensional materials with hexagonal crystal symmetry offers a new electronic degree of freedom, namely valley, the manipulation and detection of which could potentially be exploited to form new many-body ground states as well as new paradigms of electronic applications. In this talk, I will describe our work in creating valley-momentum locked quantum wires, namely quantum valley Hall kink states, in Bernal stacked bilayer graphene and show the operations of a waveguide, a valley valve and a tunable electron beam splitter, based on unique attributes of this new helical 1D system. The quantum valley Hall kink states are created by generating a topological band structure in bilayer graphene using multiple gates and exhibit quantized conductance of 4e^2/h. The high quality and versatile controls of this new helical 1D system open the door to many exciting possibilities in low-dimensional and topological systems.
J. Li, K. Wang, K. J. McFaul, Z. Zern, Y. Ren, K. Watanabe, T. Taniguchi, Z. Qiao, and J. Zhu, Gate-controlled topological conducting channels in bilayer graphene, Nature Nanotechnology 11, 1060 (2016).
J. Li, R.-X. Zhang, Z. Yin, J. Zhang, K. Watanabe, T. Taniguchi, C. Liu, and J. Zhu, A valley valve and electron beam splitter in bilayer graphene, arXiv:1708.02311v1 (2017).