Stability of the bilayer ν=1 quantum Hall state under charge imbalance

Abstract

We study the stability of the bilayer ν tot=1 quantum Hall (QH) state in a high mobility bilayer hole sample as carriers are transferred from one layer to the other while maintaining a constant total carrier density. For a total carrier density n tot =1.2×10 11 cm −2 , we show that the stability of the charge imbalanced QH state remains constant for small charge transfer, before increasing monotonically as the layer densities are imbalanced further. This behaviour is consistent with the predictions of Hartree–Fock mean field theory, but is contrary to previous experiments where a monotonic increase in the stability is observed. However, this monotonic increase in the stability can be reproduced in our samples at low density when n tot =8.2×10 10 cm −2 . The difference between experimental data and Hartree–Fock theory as total density is decreased suggests that excitations other than the quasiparticle and collective excitations may become significant.