Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 58: Transport: Poster Session

TT 58.43: Poster

Mittwoch, 9. März 2016, 15:00–18:30, Poster D

Spin-Transport in Graphene with Agregated Hydrogen Clusters — •Fedor Tkatschenko, Jan Bundesmann, Denis Kochan, Jaroslav Fabian, and Klaus Richter — Institut für Theoretische Physik Universität Regensburg

Hydrogen on graphene acts as resonant impurity and in addition can lead to formation of local magnetic moments. Both effects reduce the spin lifetime by orders of magnitude [1]. This can explain the discrepancy between predicted long spin lifetimes compared to the short ones measured in experiments. However, some experiments report a longer spin lifetime after increasing the H concentration [2].

We argue that above some threshold concentration the probability for formation of H-clusters like dimers or trimers strongly increases. The collective impact from H-clusters can differ from isolated H-atoms. This is reflected in the systems electronic structure. Using a single-orbital tight binding approach we calculate the electronic structure for H-clusters on graphene which is shown to be in good agreement with DFT calculations. Furthermore we perform quantum transport calculations and extract the influence on the spin lifetime. We find that the exact configuration of the clusters like the sublattice occupation is essential, as it decides whether magnetic moments are formed or the position of the resonant state.
D. Kochan, M. Gmitra and J. Fabian, PRL 112, 116602 (2014)
M. Wojtaszeck, I. J. Vera-Marun, T. Massen and B. J. van Wees,

PRB 87, 081402(R) (2013)