Research Unit 912 - Coherence and relaxation properties of electron spins

Motivation

The spin is an additional degree of freedom of an electron which is expected to lead to a change of paradigm for information processing. Within the emerging field of spintronics, proposed schemes for novel information units are, 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 as evidenced by magnon heat transport. 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.

Research Topics

Within this research unit, we tackle the fundamentals of spin relaxation and coherence. On the one hand, we investigate III-V-semiconductors, which serve as a reference and as a model system 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 materials classes, the intricate nature of spin dynamics requires a strong theoretical backing including novel numerical methods for a versatile application to the different materials classes. These approaches will be developed based on the current forefront approaches in, e.g., density functional, quantum Monte Carlo, and time-dependent density matrix renormalization group methods.

Speakers of the Research Unit

Professor Dr. M. Morgenstern:

Adress:
II. Institute of Physics B - RWTH Aachen University
Otto-Blumenthal-Straße - Turm 28
52074 Aachen
Contact

Professor Dr. G. Güntherodt:

Adress:
II. Institute of Physics A - RWTH Aachen University
Otto-Blumenthal-Straße - Turm 28
52074 Aachen
Contact