Quasiparticle tunneling in the lowest Landau level

Abstract

We measure quasiparticle tunneling across a constriction in the first Landau level. In the limit of weak backscattering, the dependence of the tunneling conductance on temperature and dc-bias is in qualitative disagreement with existing theories. For stronger backscattering, data obtained in the ν=1/3 state can be fitted to weak backscattering theory with the predicted effective fractional charge of e∗=e/3. The scaling parameter g is however not universal and depends strongly on the gate voltage applied to the constriction. At ν=4/3, a more complex picture emerges. We propose an interpretation in terms of selective tunneling between the multiple modes present at the edge.