Monday, July 1, 2013

1306.6875 (Guang Yang et al.)

Influence of device geometry on tunneling in $ν=5/2$ quantum Hall

Guang Yang, D. E. Feldman
Two recent experiments [I. P. Radu {\it et al.}, Science $\mathbf{320}$, 899 (2008) and X. Lin {\it et al.}, Phys. Rev. B $\mathbf{85}$, 165321 (2012)] measured the temperature and voltage dependence of the quasiparticle tunneling through a quantum point contact in the $\nu= 5/2$ quantum Hall liquid. The results led to conflicting conclusions about the nature of the quantum Hall state. In this paper, we show that the conflict can be resolved by recognizing different geometries of the devices in the experiments. We argue that in some of those geometries there is significant unscreened electrostatic interaction between the segments of the quantum Hall edge on the opposite sides of the point contact. Coulomb interaction affects the tunneling current. We compare experimental results with theoretical predictions for the Pfaffian, $SU(2)_2$, 331 and K=8 states and their particle-hole conjugates. After Coulomb corrections are taken into account, measurements in all geometries agree with the spin-polarized and spin-unpolarized Halperin 331 states.
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