Regensburg 2016 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 52: Focus: Ultrafast spin currents for spin-orbitronics: from metals to topological insulators
MA 52.2: Hauptvortrag
Freitag, 11. März 2016, 10:00–10:30, H32
Ultrafast photocurrents and quantized conductance in 3D topological insulators — •Alexander Holleitner — Walter Schottky Institut and Physics Department, Technical University of Munich, Am Coulombwall 4a, 85748 Garching
We demonstrate that helicity-dependent photocurrents in 3D topological insulators can be controlled and read-out on a time-scale of a picosecond with near-unity fidelity even at room temperature [1,2]. Our experiments reveal the temporal interplay of such ultrafast spin currents with photo-induced thermoelectric currents of hot electrons in the optoelectronic circuits. Moreover, we verify millimeter-scale edge channels in bismuth chalcogenides with a quantized conductance of 1 e2/h at zero magnetic field. In optoelectronic experiments [3], the quantum transport is found at the lateral edges of the 3D topological insulators and is explained by a one-dimensional quantum confinement of non-topological surface states with a strong Rashba spin-orbit coupling [4].
We thank C. Kastl, P. Seifert, C. Karnetzky, H. Karl, X. He, K. Wu, and Y. Li, for a very fruitful collaboration, and the DFG-SPP-1666 ‘Topological insulators’ and the ERC-grant ‘NanoREAL’ for financial support.
[1] L. Prechtel et al. Nature Comm. 3, 646 (2012).
[2] C. Kastl et al. Nature Comm. 6, 6617 (2015).
[3] C. Kastl et al. 2D Materials 2, 024012 (2015).
[4] C. Kastl et al. (2016).