Advancing Cryogenic Cooling with Self-Modulated YbAgCu4 for Enhanced Thermoelectric Efficiency below Liquid-Nitrogen Temperatures

Abstract

This report presents a comprehensive study of the thermoelectric performance of self-modulated YbAgCu4 for cryogenic cooling, T < 50 K. Implementing self-modulation-based nanostructuring by spark-plasma-sintering of powdered sintered and as-spun ribbons together, we obtained a high power factor of ∼2.3 × 10-2 W·m-1·K-2. The grain-boundary scattering in the prepared nanostructured samples significantly decreased the thermal conductivity as compared to the earlier reported values in polycrystalline YbAgCu4. In the present work, the peak thermoelectric figure-of-merit ZT of ∼0.32 at ∼43 K was achieved in the modulated sample. Such never before achieved high ZT at this temperature establishes the applicability of present methodology for cryogenic cooling below 77 K, which could further be extended to other heavy-Fermion materials to enhance their thermoelectric performances. © 2023 American Chemical Society.