FOR 912: Coherence and Relaxation Properties of Electron Spins

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The spin is the additional degree of freedom of an electron, which can lead to a change in paradigm of present-day charge-based information processing. Within the emerging field of spintronics, proposed schemes for novel information units include, e.g., spin valves, spin transistors and spin qubits. All these concepts require a low spin relaxation rate and for qubits the coherence of spin states. In this respect, binary semiconductors have been intensively studied so far, but it is apparent that alternative materials are potentially more advantageous with respect to spin relaxation and coherence. In particular, carbon based materials such as carbon nanotubes or graphene could ultimately provide a reduced spin relaxation and decoherence, since they are less affected by spin-orbit and hyperfine coupling. Other, even less conventional materials such as one-dimensional quantum magnets might be even more prospective by providing pure spin excitations, resulting in an intrinsically dissipationless spin transport for particular systems. Importantly, the limiting channels for spin decoherence and relaxation are neither known for the C-based materials nor for the quantum magnets strongly requiring exploratory research. Within this Research Unit, we will tackle the fundamentals of spin relaxation and coherence. On the one hand, we will investigate the III-V-semiconductors, which serve as a reference and as model systems to introduce novel cutting-edge methodology with respect to spin coherence and manipulation. On the other hand, we will tackle the novel materials by determining their dynamic spin properties and introducing novel concepts for an envisioned spin functionality. In all three material classes, the intricate nature of spin dynamics requires a strong theoretical backing including novel numerical methods for a versatile application to the different material classes. These approaches will be developed based on the current forefront approaches in, e.g., DFT, QMC or TD-DMRG.