Talk by Guido Burkard, University of Konstanza – Niels Bohr Institute - University of Copenhagen

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Niels Bohr Institute > Calendar > 2010 > Talk by Guido Burkard,...

Talk by Guido Burkard, University of Konstanza

The spin blockade effect in the electric conduction through two semiconductor quantum dots connected in series has allowed the monitoring of spin-breaking effects, notably single-spin rotations induced via external fields in electron spin resonance (ESR) and spin decoherence due to the hyperfine coupling to the nuclear spin environment.

Electrons in double quantum dots in graphene and carbon nanotubes comprise a valley degree of freedom in addition to their spin. We show that this can lead to a spin-valley blockade which is sensitive to both spin and valley breaking effects. The hyperfine interaction due to residual 13C nuclear spins turns out to be both spin- and valley-breaking, while non-magnetic atomic impurities can lead to pure valley-breaking.

We study the magnetic-field dependent leakage current in the spin-valley blockade. Finally, we also take into account the effect of the spin-orbit interaction in carbon-nanotubes and its influence on the leakage current.

Talk by Guido Burkard, University of Konstanza