Development of an Improved Probe Design and Analysis Method for Reliable Thermopower Measurements

Abstract. Thermopower is a fundamental thermodynamic property that provides insight into the behavior of strongly correlated electron materials, such as their scattering time and density of state. Quantified by the Seebeck coefficient, this value represents the ratio of voltage generated over the temperature gradient applied across a sample. In our lab, previous thermopower measurements were hindered by lengthy experiments and complicated analysis. To improve efficiency, we implemented a faster analysis technique and began directly regulating temperature on the cold-side thermometer. Testing with 99.95% platinum showed consistent results between the slope and steady-state methods under a temperature gradient ~3% above the regulated cold-side temperature, as well as agreement with literature above 40 K. Deviations below 40 K were attributed to the differential type-T thermocouple, which has limited resolution for low-temperature measurements. These results confirm the slope method’s validity, the use of the thermocouple as a reference sample, and our probe’s overall effectiveness above 40 K. To enhance sub-40-K accuracy, we are developing a new probe incorporating a hot-side thermometer and simultaneous measurement of target and reference samples, enabling more precise removal of background contributions.