Achieving efficient thermoelectric cooling at cryogenic temperatures is crucial for advancing electronics and quantum materials applications. This study develops nanoscale cryogenic imaging of the magneto-thermoelectric effect and demonstrates absolute cooling and the Ettingshausen effect in WTe₂ Weyl semimetal flakes at liquid helium temperatures. Unlike bulk materials, cooling exhibits non-monotonic behavior with respect to magnetic field and device size. A model reveals that cooling efficiency and temperature profiles are determined by the interplay of sample geometry, electron-hole recombination length, magnetic field, and flake and substrate heat conductivities. These findings pave the way for integrating microscopic thermoelectric cooling and temperature landscape engineering in van der Waals devices.

T. Völkl, A. Aharon-Steinberg, T. Holder, E. Alpern, N. Banu, A. K. Pariari, Y. Myasoedov, M. E. Huber, M. Hücker, E. Zeldov