Dresden 2011 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 64: Quantum Wires: Transport
HL 64.2: Vortrag
Mittwoch, 16. März 2011, 16:45–17:00, POT 251
Mode-filtered electron injection into a waveguide interferometer — •S.S. Buchholz1, S.F. Fischer1, U. Kunze1, D. Reuter2, and A.D. Wieck2 — 1Werkstoffe und Nanoelektronik — 2Angewandte Festkörperphysik, Ruhr-Universität Bochum
Injection of mode-filtered electrons into a phase-sensitive waveguide Aharonov-Bohm (AB) ring is studied for the lowest one-dimensional (1D) transport mode. An individually tuneable quantum point contact (QPC) couples coherently to 1D modes in the ring. Thus, we demonstrate single-mode transport in a multi-mode waveguide structure.
QPCs and electronic waveguides (EWGs) show the distinctive property of quantized transverse momentum resulting in conductance quantization, which makes them attractive as electronic beam splitters and sensitive single charge detectors. QPCs in the “0.7-anomaly” have been discussed as all-electrical spin polarizers. The degree of spin polarization can be probed in a quantum ring - quantum dot device.1 However, in order to investigate QPCs as spin polarizers, firstly their application as mode-filters in the lowest subband calls for experimental realization.
Here, we study transport in an EWG interferometer2 (etched from a GaAs/AlGaAs-heterostructure) in which a QPC is embedded in one of the waveguide leads. The QPC was tuned to the regime of the first and second subbands. By means of bend resistance and electron interference, we show that the selective coupling of 1D subbands in the EWGs to modes in the QPC leads to coherent mode-filtered transport.
[1] B. Hiltscher et al., Phys. Rev. B 82, 165452 (2010).
[2] S.S. Buchholz et al., Phys. Rev. B 82, 045432 (2010).