Magneto-coulomb oscillations in GaAs-AlGaAs quantum dot structures |
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| Institution: | 1. Department of Material Science and Engineering and Department of Chemistry, Indian Institute of Technology, Palaj, Gandhinagar 382355, India;2. Materials Research Centre, Indian Institute of Science, Bangalore 560012, India;3. Materials Science and Nanoengineering, Rice University, Houston, TX 77005, USA;4. New Industry Creation Hatchery Center, Tohoku University, 4-4-6 Aramaki aza Aoba, Aoba-ku, Sendai 980-8579, Japan;5. Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson AFB, OH 45433-7718, USA;6. Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur, West Bengal, India;1. State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100101, China;2. Department of Geography, University of Toronto, 100 St. George St., Toronto, ON, Canada;3. Biometeorology Research Laboratory, Vancouver Island University, Nanaimo, BC, Canada;4. Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada;1. Department of Medicine, VA Palo Alto Health Care System, Palo Alto, California, USA;2. Department of Medicine, Stanford University, Palo Alto, California, USA |
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| Abstract: | We report on experiments of the magnetotransport properties of GaAs-AlGaAs lateral quantum dots. At high magnetic fields for a 1 μm square dot structure, current flow occurred via edge states and, with the point contacts adjusted to allow transmission of one or more edge states, a strong backscattering resonance followed by short period oscillations were observed in the magnetoresistance, as B increased. At higher fields for a 2 μm dot, we observe a rapid rise in the magnetoresistance associated with the depopulation of the point contacts and the isolation of the dot from the leads. At still higher fields there occur periodic oscillations whose period was two orders of magnitude larger than would result from interference, or Aharonov-Bohm type effects.We analyze these phenomena using self-consistent electronic structure calculations for our devices. In particular, we show that the evolution of the terrace like structure of the potential profile profoundly affects the single particle spectrum within the dot when several Landau levels are occupied. For the large dot device, we expect that in the high field regime with the dot isolated from the leads, only a single Landau level is occupied in both the dot and the 2DEG region. In this regime, tunneling into and out of the dot is regulated by charging effects. We have introduced a "magneto-Coulomb oscillations" explanation of the periodic resonances that are observed. |
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