Interference effects in transport across a single incompressible strip at the edge of the fractional quantum Hall system

We experimentally investigate interference effects in transport across a single incompressible strip at the edge of the quantum Hall system by using a Fabry-Perot type interferometer. We find the interference oscillations in transport across the incompressible strips with local filling factors $ u_c=1, 4/3, 2/3$ even at high imbalances, exceeding the spectral gaps. In contrast, there is no sign of the interference in transport across the principal Laughlin $ u_c=1/3$ incompressible strip. This indicates, that even at fractional $ u_c$, the interference effects are caused by normal electrons. The oscillations period is determined by the effective interferometer area, which is sensitive to the filling factors because of screening effects.

Experimental realization of a Fabry-Perot-type interferometer by co-propagating edge states in the quantum Hall regime

A Fabry-Perot-type interferometer is experimentally realized for electrons in a semiconductor device. A special experimental geometry creates interference conditions for co-propagating electrons in quantum Hall edge states, which results in oscillations of the current through the device. The visibility of these oscillations is found to increase at the high-field edge of the quantum Hall plateau.

Separately contacted edge states at high imbalance in the integer and fractional quantum Hall effect regime

This review presents experimental results on the inter-edge-state transport in the quantum Hall effect, mostly obtained in the regime of high imbalance. The application of a special geometry makes it possible to perform I-V spectroscopy between individual edge channels in both the integer and the fractional regime. This makes it possible to study in detail a number of physical effects such as the creation of topological defects in the integer quantum Hall effect and neutral collective modes excitation in fractional regime. The while many of the experimental findings are well explained within established theories of the quantum Hall effects, a number of observations give new insight into the local structure at the sample edge, which can serve as a starting point for further theoretical studies.

Manifestation of a complex edge excitation structure in the fractional quantum Hall regime at high filling factors

We experimentally study equilibration across the sample edge at high fractional filling factors 4/3, 5/3 under experimental conditions, which allow us to obtain high imbalance conditions. We find a lack of the full equilibration across the edge even in the flat-band situation, where no potential barrier survives at the sample edge. We interpret this result as the manifestation of complicated edge excitation structure at high fractional filling factors 4/3, 5/3. Also, a mobility gap in the $ u_c=1$ incompressible strip is determined in normal and tilted magnetic fields.