Jun Zhu (Penn State)
Thu. August 31st, 2017, 4:00 pm-5:00 pm
Rockefeller 301 Add to Google Calendar
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).