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HL: Fachverband Halbleiterphysik

HL 8: Transport and theory of electronic structure

HL 8.3: Vortrag

Montag, 1. April 2019, 15:30–15:45, H33

Magnetotunneling Spectroscopy of Imbalanced Double Quantum Wells — •Gunnar Lasse Schneider¹, Werner Dietsche², and Rolf J. Haug¹ — ¹Institut für Festkörperphysik, Leibniz Uni Hannover, Deutschland — ²MPI for Solid State Research, Stuttgart, Germany

Since several years bilayer phenomena such as 2D-2D Tunneling [1], Coulomb drag [2] and excitonic Bose-Einstein condensates (BEC) [3] are observable within double quantum wells in the Quantum Hall regime. Most studies were focused on balanced systems (i.e. the BEC was first found to arise at balanced layer densities with the filling factor combination of 1/2 and 1/2). In our work we are investigating imbalanced layers, allowing a mapping of the magnetotunneling characteristics at various filling factor combinations and the evolution of the excitonic condensate in the charge carrier density space.

All measurements were performed on a MBE grown GaAs double quantum well separated by a 10 nm AlAs/GaAs barrier. Each layer is individually contacted using field gates for a local depletion [4]. Additional gates allow tuning the charge carrier densities between 1E10 and 4E10 per square centimeter. Our measurements show Quantum Hall selection rules in the magnetotunneling characteristics (Quantum Hall spin diode) and the transition towards excitonic condensation.

[1]N. Turner et al., Phys. Rev. B 54, 10614 (1996)

[2]C. Jörger et al., Physica E 6, 586 (2000)

[3]J.P. Eisenstein and A.H. MacDonald, Nature 432, 691 (2004)

[4]J.P. Eisenstein et al., Appl. Phys. Lett. 57, 2324 (1990)