Experimental setup for the Seebeck and Nernst coefficient measurements.

Abstract

A new experimental setup is designed for the measurement of Seebeck and Nernst coefficients on the single crystal flakes and polycrystalline samples. The setup utilizes the multifunctional probe assembly of the physical property measurement system by Quantum Design, Inc. and can measure in the temperature range of 1.8 K-380 K up to 8 T magnetic fields. The experimental measurement was fully automated through a computer using the code written in LabVIEW software. The setup is capable of measurements on samples as small as 2 × 1 mm2 in size and thickness as small as a few micrometers, which is quite important for the crystal flakes grown using the vapor transport method. The determination of the coefficients is based on the quasi-static approach, with the thermal gradient of 0.2 K-1.2 K across the sample in the measured temperature range of 1.8 K-300 K. The sensitivity of the instrument is better than 0.1 µV/K, and the accuracy is better than ∼0.5 µV/K, which can be further improved with the better quality of electrical contacts on the sample. The Seebeck and Nernst coefficient measurements performed on some well-studied semimetallic (bismuth), thermoelectric (Bi2Se3), and superconducting (FeTe0.5Se0.5) systems are also presented.