ESPCI web site
September 11 at 2:00 pm (Paris time)
Room Holwek, building C, 1st floor, 10 rue Vauquelin, ESPCI,
Local probing of transverse thermoelectric effects in meso- and nano scale devices
Solid-state cooling devices offer compact, quiet, reliable, and environmentally friendly solutions, which currently rely on conventional thermoelectric (TE) effects. However, despite more than two centuries of research, classical thermoelectric coolers remain limited by low efficiency, restricting their broader application. In our work, we explore transverse thermoelectric effects as an alternative pathway for on-chip cooling. Using our unique scanning thermal microscopy methodology, we are able to locally probe several transverse effects—such as the anomalous Ettingshausen effect (AEE), local Nernst effects, and local spin Seebeck effects—on the nanoscale. This approach allows us to directly study the influence of defects, interfaces, or magnetic textures on thermoelectric performance, thus opening up new routes for engineering high-efficiency devices. As a concrete example, we demonstrate that the AEE can be strongly enhanced in materials with non-trivial band topologies, such as the Heusler alloy Co2MnGa. In situ scanning thermal microscopy reveals a record-breaking room-temperature anomalous Ettingshausen coefficient in µm-sized Co2MnGa devices. Furthermore, by fabricating nanoribbon devices, we induce a geometrical Peltier effect that increases the figure of merit by 170%. The combined cooling action of the anomalous Ettingshausen and Peltier effects yields a nm-sized local spot cooler, highlighting the unique potential of nanostructured magnetic Weyl semimetals for solid-state thermal management.
