Thursday, July 18, 2013

1307.4408 (F. Amet et al.)

Gate control of spin and valley polarized quantum Hall edge states in

F. Amet, J. R. Wiliams, K. Watanabe, T. Taniguchi, D. Goldhaber-Gordon
We report on transport measurements of dual-gated single-layer graphene devices in the quantum Hall regime, allowing for independent control of the filling-factors in adjoining regions. At a high magnetic field, the spin and valley degeneracy of the n=0 and n=1 Landau levels are fully lifted, and the corresponding edge states are therefore polarized, making it possible to investigate interactions between edge states with different SU(4) polarizations. We show that such interactions preserve spin but not valley polarization. The pattern of equilibration supports the experimental evidence [1] that the n=1 Landau level is spin-polarized at half-filling. The conductance in the bipolar regime is strongly suppressed, indicating that co-propagating edge states do not equilibrate along p-n interfaces.
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