Anomalous thermopower of a quasi-two-dimensional low-density metallic hole gas

Abstract

We study the thermopower $S$ and the resistance $R$ of a low-density quasi-two-dimensional hole gas in the metallic regime at low temperatures ($T$’s). Long-range interface-roughness fluctuations are found to explain the sign anomaly and the sign reversal of the recently observed $T$-dependent $S$. Two mechanisms showing similar $S$($R$) can yield very different $R$($S$), indicating that $S$ and $R$ play a complementary role toward understanding the transport mechanism.