We have measured diffusion thermopower in a two-dimensional electron gas at low temperature (T=40 mK) in the field range 0 <B< 3.4 T, by employing the current heating technique. A Hall bar device is designed for this purpose, which contains two crossing Hall bars, one for the measurement and the other used as a heater, and is equipped with a metallic front gate to control the resistivity of the areas to be heated. In the low magnetic field regime (B≤ 1 T), we obtain the transverse thermopower Syx that quantitatively agrees with the Syx calculated from resistivities using the generalized Mott formula. In the quantum Hall regime (B≥ 1T), we find that Syx signal appears only when both the measured and the heater area are in the resistive (inter-quantum Hall transition) region. Anomalous gate-voltage dependence is observed above ∼1.8 T, where spin-splitting in the measured area becomes apparent.
@article{arxiv.0909.1403,
title = {Measurement of diffusion thermopower in the quantum Hall systems},
author = {K. Fujita and A. Endo and S. Katsumoto and Y. Iye},
journal= {arXiv preprint arXiv:0909.1403},
year = {2010}
}