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TT: Fachverband Tiefe Temperaturen
TT 1: TR: Graphene 1
TT 1.7: Vortrag
Montag, 22. März 2010, 12:00–12:15, H18
Hyperfine interaction and electron-spin decoherence in graphene and carbon nanotube quantum dots — •Jan Fischer1, Bjoern Trauzettel2, and Daniel Loss1 — 1Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland — 2Institute of Theoretical Physics and Astrophysics, University of Würzburg, D-97074 Würzburg, Germany
We analytically calculate the nuclear-spin interactions of a single electron confined to a carbon nanotube or graphene quantum dot [1]. While the conduction-band states in graphene are p-type, the accordant states in a carbon nanotube are sp-hybridized due to curvature. This leads to an interesting interplay between isotropic and anisotropic hyperfine interactions. By using only analytical methods, we are able to show how the interaction strength depends on important physical parameters, such as curvature and isotope abundances. We show that for the investigated carbon structures, the 13C hyperfine coupling strength is less than 1 µeV, and that the associated electron-spin decoherence time can be expected to be several tens of microseconds or longer, depending on the abundance of spin-carrying 13C nuclei. Furthermore, we find that the hyperfine-induced Knight shift is highly anisotropic, both in graphene and in nanotubes of arbitrary chirality.
[1] J. Fischer, B. Trauzettel, D. Loss, Phys. Rev. B 80, 155401 (2009)
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