Spin coherence, spin qubits, and spin transport in carbon nanostructures

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This theory project deals with spin coherence and magnetic interactions in carbon- based nanostructures such as quantum dots (QDs), nanoflakes, nanoribbons (GNRs), and carbon nanotubes (CNTs), as well as extended graphene. We focus on: (1) Spin properties of localized electrons in QDs and nanoflakes which can deviate substantially from that of mobile spins. Spin physics in QDs based on quasi-1D materials (GNRs, CNTs) are expected to be different from 2D structures. (2) Spin coherence and relaxation of mobile electrons in graphene have been studied experimentally [1], but several aspects such as their anisotropy are not understood at this point. Further motivation comes from the potential use as qubits where coherence is essential. Carbon is an unconventional but promising material for spin qubits and other spintronics applications. In contrast to III-V semiconductors, spin-orbit coupling in carbon is weak, allowing for long spin relaxartion times T1. Carbon also has very dilute nuclear spins, allowing for long spin coherence times T2. We propose to continue an existing project (results from the first funding period, see below). The topic of the project is unchanged, with these important adjustments: (1) The project is extended and now lead by two principal investigators (C. Honerkamp of RWTH Aachen applies to join the Research Unit). (2) The project is more focused in terms of materials, as we now concentrate on carbon where we have achieved the best results in the first funding period and which is in line with the regrouping of the other projects.