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DS: Fachverband Dünne Schichten
DS 15: Thermoelectric and Phase Change Materials
DS 15.6: Vortrag
Donnerstag, 21. März 2024, 11:45–12:00, A 060
Imaging the Ettingshausen effect and cryogenic thermoelectric cooling in a van der Waals semimetal — •Tobias Völkl1, Amit Aharon-Steinberg1, Tobias Holder1,2, Edan Alpern1, Nasrin Banu1, Arnab Pariari1, Yuri Myasoedov1, Martin Huber3, and Eli Zeldov1 — 11Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel — 2School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel — 3Departments of Physics and Electrical Engineering, University of Colorado Denver, Denver, Colorado
Attaining viable thermoelectric cooling at cryogenic temperatures is of major fundamental and technological interest for novel electronics and quantum materials applications. Here we develop nanoscale cryogenic imaging of a magneto-thermoelectric effect and demonstrate absolute cooling and an ultrahigh Ettingshausen effect in exfoliated WTe2 Weyl semimetal flakes at liquid He temperatures. Application of a current and perpendicular magnetic field gives rise to cooling via generation of electron-hole pairs on one side of the sample and heating by their recombination at the opposite side. In contrast to bulk materials, the cooling process is found to be nonmonotonic in magnetic field and in device size. The derived model of magneto-thermoelectricity in mesoscopic semimetal devices shows that the cooling efficiency and the induced temperature profiles are governed by the interplay between sample geometry, electron-hole recombination length, magnetic field, and flake and substrate heat conductivities.
Keywords: Ettingshausen; Thermoelectric; Cooling; van der Waals; SQUID