Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 22: Graphene: Structure and Theory II

HL 22.1: Talk

Monday, March 26, 2012, 17:15–17:30, EW 201

DFT+CI calculations of quantum dots in graphene nanoribbons — •Tobias Burnus¹, Gustav Bihlmayer¹, Daniel Wortmann¹, Ersoy Sasioglu¹, Stefan Blügel¹, and Klaus Michael Indlekofer² — ¹Peter Grünberg Institut & Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany — ²Hochschule RheinMain, Unter den Eichen 5, 65195 Wiesbaden, Germany

Graphene nanoribbons (GNR) hold great future promise for field-effect transistors and quantum-dot devices. With gate electrodes an in-plane electric field can be generated, which localizes quantum-dot states in the bandgap of armchair GNR. Density-functional theory (DFT) calculations have been used to calculate GNR under an in-plane gate electric field, taking correctly the edge termination of the ribbon into account. The results obtained via DFT have been combined with the screened Coulomb interaction calculated within the random-phase approximation to setup a configuration interaction (CI) calculation for the quantum dot, which properly describes the multiplet states of the few electrons in the quantum dot. The results of this DFT+CI calculation can be used for a description of the time-dependent spin decoherence.

The work is supported by the DFG Research Unit 912 “Coherence and Relaxation Properties of Electron Spins”.