Anomalous thermopower in the metalliclike phase of a 2D hole system
We report very low temperature ( T) thermopower and resistivity ( rho) measurements on variable-density, two-dimensional hole systems confined to GaAs quantum wells. As the hole density is lowered from 1.49x10(11) cm(-2) to 0.14x10(11) cm(-2), the system crosses from an insulating ( drho / dT less, similar0) to a metallic regime ( drho / dT>0) and finally displays insulating behavior ( drho / dT<0). Diffusion thermopower shows a striking sign reversal in a narrow range of density in the metallic regime, suggesting a qualitative change in the conduction or the scattering mechanism.
Moldovan
L
Unite de Physico-Chimie et de Physique des Materiaux, Universite Catholique de Louvain, Place Croix du Sud 1, B-1348 Louvain-la-Neuve, Belgium and Department of Electrical Engineering, University of Oradea, 3700 Oradea, Romania.
Melinte
S
Bayot
V
Papadakis
SJ
De Poortere EP
Shayegan
M