Effect of charge state in nearby quantum dots on quantum Hall effect.pdf

APS/123-QED Effect of charge state in nearby quantum dots on quantum Hall effect K. Takehana,∗ T. Takamasu, and G. Kido Nanomaterials Laboratory, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, 305-0047 Japan 5 M. Henini 0 School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK 0 (Dated: February 2, 2008) 2 Magnetoresistance measurements have been performed on a gated two-dimensional electron sys- p tem (2DES) separated by a thin barrier layer from a layer of InAs self-assembled quantum dots e (QDs). Clear features of the quantum Hall effect were observed despite the proximity of the QDs S layer to the 2DES. However, the magnetoresistance (ρxx) and Hall resistance (ρxy ) are suppressed 4 significantly in the magnetic field range of filling factor ν 1 when a positive voltage is applied to 1 the front gate. The influence of the charge state in QDs was observed on the transport properties of the nearby 2DES only in the field range of ν 1. It is proposed that the anomalous suppression of ] ρxx and ρxy is related to spin excitation, which is induced by spin-flip processes involving electrons l l in the QDs and the 2DES. a h PACS numbers: 73.43.Qt, 73.21.La - s e m I. INTRODUCTION