Laterally coupled and field-induced quantum Hall systems

Abstract

A quantum Hall system which is divided into two laterally coupled subsystems by means of a tunneling barrier exhibits a complex Landau level dispersion. Magnetotunneling spectroscopy is employed to investigate the small energy gaps which separate subsequent Landau bands. The control on the Fermi level permits to trace the anticrossings for varying magnetic fields. The band structure calculation predicts a magnetic shift of the band gaps on the scale of the cyclotron energy. This effect is confirmed experimentally by a displacement of the conductance peaks on the axis of the filling factor. Tunneling centers within the barrier are responsible for quantum interferences between opposite edge channels. Due to the disorder potential, the corresponding Aharonov-Bohm interferometers generate additional long-period and irregular conductance features. In the regime of strong localization, conductance fluctuations occur at small magnetic fields before the onset of the regular Landau oscillations. The Landau dispersion is obtained by a dedicated algorithm which solves the Schroedinger equation exactly for a single electron residing in a quantum Hall system with an arbitrary unidirectional, threefold staircase potential.

20 pages, 11 figures, 1 table; v2: explanation added in section 2, some minor changes

References in corpus (11)

• Imaging Magnetic Focusing of Coherent Electron Waves
• Tunneling between the Edges of Two Lateral Quantum Hall Systems
• Edge States in Strong Magnetic Field
• The structure of a single sharp quantum Hall edge probed by momentum-resolved tunneling
• Interedge Phase Coherence in Quantum Hall Line Junctions
• Inter edge Tunneling in Quantum Hall Line Junctions
• Tunneling gap of laterally separated quantum Hall states
• Oscillatory Tunneling between Quantum Hall Systems
• Cascade of Quantum Phase Transitions in Tunnel-Coupled Edge States
• Quantum Hall line junction with impurities as a multi-slit Luttinger liquid interferometer
• Calculation and spectroscopy of the Landau band structure at a thin and atomically precise tunneling barrier