Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 37: MLT: Poster Session
TT 37.21: Poster
Thursday, March 25, 2010, 14:00–18:00, Poster A
Spin Coherence in Graphene — •Matthias Droth and Guido Burkard — Universität Konstanz, 78464 Konstanz, Germany
Spin relaxation in a quantum dot can occur due to interaction with nuclear spins or phonons. Since µN≪µe− the former coupling is supressed for typical magnetic fields slightly above the mT regime such that phonon coupling is the dominant effect. For a rectangular dot on a graphene nano ribbon we calculate T1 assuming the relaxation to occur via spin-orbit and electron-phonon interaction as proposed in [1]. In order to obtain the spectrum and density of states of the relevant acoustic phonons we start from a continuum model and derive the dispersion relations for in-plane and out-of-plane acoustic phonons. Due to open boundary conditions at the ribbon edges the usual q2 dependence for out-of-plane modes in bulk is cut off at the zone center where we find a linear dispersion. The transverse and longitudinal sound velocities of the in-plane modes match well with literature values [2].
[1] A. V. Khaetskii, Y. V. Nazarov; Physical Review B 64, 2001
[2] L. A. Falkovsky; arXiv:0802.0912v1