We report electric detection of the spin Peltier effect (SPE) in a bilayer consisting of a Pt film and a Y3Fe5O12 (YIG) single crystal at the cryogenic temperature T as low as 2 K based on a RuO2−AlOx on-chip thermometer film. By means of a reactive co-sputtering technique, we successfully fabricated RuO2−AlOx films having a large temperature coefficient of resistance (TCR) of ∼100%K−1 at around 2K. By using the RuO2−AlOx film as an on-chip temperature sensor for a Pt/YIG device, we observe a SPE-induced temperature change on the order of sub-μK, the sign of which is reversed with respect to the external magnetic field B direction. We found that the SPE signal gradually decreases and converges to zero by increasing B up to 10T. The result is attributed to the suppression of magnon excitations due to the Zeeman-gap opening in the magnon dispersion of YIG, whose energy much exceeds the thermal energy at 2 K.
@article{arxiv.2311.01711,
title = {Cryogenic spin Peltier effect detected by a RuO$_2$-AlO$_x$ on-chip microthermometer},
author = {Takashi Kikkawa and Haruka Kiguchi and Alexey A. Kaverzin and Ryo Takahashi and Eiji Saitoh},
journal= {arXiv preprint arXiv:2311.01711},
year = {2023}
}