The influence of the long-lived quantum Hall potential on the characteristics of quantum devices

Novel hysteretic effects are reported in magneto-transport experiments on lateral quantum devices. The effects are characterized by two vastly different relaxation times (minutes and days). It is shown that the observed phenomena are related to long-lived eddy currents. This is confirmed by torsion-balance magnetometry measurements of the same 2-dimensional electron gas (2DEG) material. These observations show that the induced quantum Hall potential at the edges of the 2DEG reservoirs influences transport through the devices, and have important consequences for the magneto-transport of all lateral quantum devices.Comment: 5 pages, 4 figure

Experimente zur Potential- und Stromverteilung in Quanten-Hall-Systemen mit Einzelelektron-Transistoren

In this work we have studied the properties of two-dimensional electron systems (2DES) in AlGaAs heterostructures under quantum Hall conditions. We employed single-electron transistors (SETs) as highly sensitive and very small potential probes for the 2DES on top of quantum Hall samples. The Measurements are focused on non equilibrium situations, induced by varying the magnetic field inside the quantum Hall plateau regions. Even though the SETs are stationary devices, spatial information about the potential landscape inside the 2DES could be obtained by shifting the edge depletion region of the 2DES towards the SET by applying a negative voltage to an external sidegate located close to the SET. Using this technique, compressible and incompressible strips inside the 2DES close to the edge of the samples could be detected at magnetic field between 0.5 T and 12.5 T and at temperatures up to 500 mK. Varying the magnetic field in the integer quantum Hall regime induces a voltage between the edge and the bulk of the 2DES which is the Hall voltage of large eddy currents inside the 2DES. Using multiple single-electron transistor electrometers placed at different positions on the Hall bars, it could be shown that these eddy currents from one big loop along the edge of the samples. The voltage drop occurs within the innermost incompressible strip of the 2DES as long as the magnetic field is swept fast enough. (orig.)SIGLEAvailable from: http://deposit.ddb.de/cgi-bin/dokserv?idn=972094873 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Eddy currents in the integer quantum Hall regime spatially resolved by multiple single-electron transistor electrometers

Varying the magnetic field in the integer quantum Hall regime induces large eddy currents inside the two-dimensional electron system. Using multiple single-electron transistor electrometers as highly sensitive and very small potential probes on top of quantum Hall samples, we can show that these eddy currents are induced in the incompressible region close to the Hall bar mesa edge. (C) 2003 Published by Elsevier B.V