Topological Quantum Transport at Bilayer Graphene Domain Walls
Valleytronics is generating a lot of excitement in the high-tech industry as a potential avenue to quantum computing. Like spintronics, valleytronics offers a tremendous advantage in data processing speeds over the electrical charge used in classical electronics.
Electron valley, a degree of freedom that is analogous to spin, can lead to novel topological phases in bilayer graphene. A tunable bandgap can be induced in bilayer graphene by an external electric field, and such gapped bilayer graphene is predicted to be a topological
insulating phase protected by no-valley mixing symmetry, featuring quantum valley Hall effects and chiral edge states. Observation of such chiral edge states, however, is challenging
because inter-valley scattering is induced by atomic-scale defects at real bilayer graphene edges. Recent theoretical work has shown that domain walls between AB- and BA-stacked bilayer graphene can support protected chiral edge states of quantum valley Hall insulators.
We experimentally discovered topologically protected one-dimensional electron conducting channels at the domain walls of bilayer graphene. These conducting channels are “valley polarized,” which means they can serve as filters for electron valley polarization in future devices such as quantum computers.
Valleytronics is generating a lot of excitement in the high-tech industry as a potential avenue to quantum computing. Like spintronics, valleytronics offers a tremendous advantage in data processing speeds over the electrical charge used in classical electronics.
Electron valley, a degree of freedom that is analogous to spin, can lead to novel topological phases in bilayer graphene. A tunable bandgap can be induced in bilayer graphene by an external electric field, and such gapped bilayer graphene is predicted to be a topological
insulating phase protected by no-valley mixing symmetry, featuring quantum valley Hall effects and chiral edge states. Observation of such chiral edge states, however, is challenging
because inter-valley scattering is induced by atomic-scale defects at real bilayer graphene edges. Recent theoretical work has shown that domain walls between AB- and BA-stacked bilayer graphene can support protected chiral edge states of quantum valley Hall insulators.
We experimentally discovered topologically protected one-dimensional electron conducting channels at the domain walls of bilayer graphene. These conducting channels are “valley polarized,” which means they can serve as filters for electron valley polarization in future devices such as quantum computers.
Related publications:
Topological valley transport at bilayer graphene domain walls, Nature (2015) doi:10.1038/nature14364.
Highlights from Lawrence Berkeley National Lab.
<< back to Research