Hyperfine interaction and electron-spin decoherence in graphene and carbon nanotube quantum dots

Jan Fischer, Björn Trauzettel, and Daniel Loss
Phys. Rev. B 80, 155401 – Published 1 October 2009

Abstract

We analytically calculate the nuclear-spin interactions of a single electron confined to a carbon nanotube or graphene quantum dot. 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 C13 hyperfine coupling strength is less than 1μeV, 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 C13 nuclei. Furthermore, we find that the hyperfine-induced Knight shift is highly anisotropic, both in graphene and in nanotubes of arbitrary chirality.

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  • Received 19 June 2009

DOI:https://doi.org/10.1103/PhysRevB.80.155401

©2009 American Physical Society

Authors & Affiliations

Jan Fischer1, Björn 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

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Issue

Vol. 80, Iss. 15 — 15 October 2009

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