Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 37: Quantenpunkte und -drähte: Transporteigenschaften
HL 37.4: Vortrag
Donnerstag, 11. März 2004, 11:00–11:15, H13
Spin effects in quantum dots — •Jens Könemann1, D. K. Maude2, V. Avrutin3, A. Waag3, and R. J. Haug1 — 1Institut für Festkörperphysik, Universität Hannover, Appelstrasse 2, D-30167 Hannover, Germany — 2High Magnetic Field Laboratory, CNRS, 25 Avenue des Martyrs, BP 166, F-38042 Grenoble cedex 9, France — 3Abteilung Halbleiterphysik, Universität Ulm, Albert-Einstein-Allee 45,D-89069 Ulm, Germany
We present spin-resolved measurements of the transport spectrum of an individual localized state in a double-barrier resonant tunneling device probed by single-electron tunneling [1]. We investigated the spin splitting of ground and excited states and found a deviation to a linear increase of spin splitting with magnetic field beyond 18 T. Astonishingly, we observed at high magnetic fields above 14 T a flip of the resonance position of the energetically higher spin component to a lower energy, whereas the other spin-component remained unchanged. A hysteresis effect appeared at the spin flip region as well. Such "spin-flip" behaviour was observed on different Fock-Darwin levels, where it occurred at different magnetic fields. We relate this effect to the presence of magnetic impurities residual inside the quantum well.
[1] J. Könemann et al., to appear in Physica E