T. Schumann, N. Meyer, G. Mussler, J. Kampmeier, D. Grützmacher, E. Schmoranzerova, L. Braun, T. Kampfrath, J. Walowski, and M. Münzenberg:
? ( ), ? (2019), pp.?;
arXiv:1810.12799 [cond-mat.mes-hall] (2018), pp. 15;
DOI: arXiv:1810.12799 [cond-mat.mes-hall]
The theoretical prediction of topological insulators in 2007 triggered tremendous interest. They are of fundamental interest because of their topological twist in k-space, which comes along with unidirectional, spin-polarized surface-state currents, required for spin-optoelectronics. This property makes topological insulators on one hand perfect materials for optically generated, ultrafast spin-bunches spin-current sources for the generation of THz radiation. On the other hand, those spin-polarized surface-state currents when generated by a voltage lead to large spin Hall effects, or when generated by a temperature gradient to the thermal analogue, the spin Nernst effect. Both mutually convert charge/ heat currents into transverse spin currents leading to spin accumulations. By connecting both research fields, we show the evidence of heat-transport related spin Hall effects that can be extracted from opto-transport experiments. This heat-driven spin Nernst effect drives a transverse spin-current and affects the optical spin-orientation in the three-dimensional topological insulator. This manifests as a modification of the circular polarization-dependent photocurrent. We illuminate the detailed thermocurrent distribution, including the influence of edges and contacts, in spatially resolved current maps.
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