Promotie R.J. Skolasiński: nanodevices

23 mei 2018 12:30 - Locatie: Aula, TU Delft - Door: webredactie

Topology, Magnetism, and Spin-Orbit: A Band Structure Study of Semiconducting Nanodevices. Promotor: Prof.dr. Y.V. Nazarov (TNW).

Quantum spin Hall materials provide a pathway for electrons to flow along the edge without experiencing resistance. Earlier modelling has predicted that magnetic field should turn quantum spin Hall materials insulating. Contrary to the expectations, the experiments showed that electrons keep moving without the resistance even at very high magnetic fields. We go beyond simplified models used before and do a more detailed analysis of the experimental system. We find that electrons flowing along the edge have a large momentum and because of that they are able to continue moving even in presence of strong magnetic fields.

Effect of magnetic field is usually reduced in a lower dimensional materials compared to the effect that it has on a bulk materials. However, recent experiments surprisingly reported that some systems show the opposite behaviour. Our theoretical and numerical analysis of the problem reveals that the interplay between the electrons angular momentum and spin, an intrinsic property that is particularly relevant in quantum mechanics, can explain this surprising and counter intuitive observation.

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