Regensburg 2019 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 3: Topological Insulators (joint session TT/MA)
TT 3.11: Talk
Monday, April 1, 2019, 12:15–12:30, Theater
On-demand thermoelectric generation of equal-spin Cooper pairs — •Felix Keidel1, Pablo Burset2, Sun-Yong Hwang3, Björn Sothmann3, and Björn Trauzettel1 — 1Institute for Theoretical Physics and Astrophysics, University of Würzburg, D-97074 Würzburg, Germany — 2Department of Applied Physics, Aalto University, 00076 Aalto, Finland — 3Theoretische Physik, Universität Duisburg-Essen and CENIDE, D-47048 Duisburg, Germany
A central goal for the application of superconductors in spintronics is the on-demand generation of spin-polarized supercurrents or, analogously, of equal-spin Cooper pairs. Most proposals rely on a careful manipulation of magnetic materials to electrically generate equal-spin Cooper pairs in ferromagnet (F)-superconductor (S) hybrid junctions.
Here, we propose a quantum heat engine that utilizes the helicity of the edge states of a quantum spin Hall insulator instead, where nonlocal transport necessarily takes place through equal-spin channels. We demonstrate that a temperature bias applied to an S-F-S junction can drive a nonlocal polarized supercurrent, while the normal contribution from electron tunneling is suppressed. Remarkably, the relative phase between the superconductors serves as a switch to turn the thermoelectric current on and off, allowing for the creation of equal-spin Cooper pairs on demand.