Highly enhanced thermopower in two-dimensional electron systems at millikelvin temperatures.
We report experimental observation of an unexpectedly large thermopower in mesoscopic two-dimensional (2D) electron systems in GaAs/AlGaAs heterostructures at sub-Kelvin temperatures and zero magnetic field. Unlike conventional nonmagnetic high-mobility 2D systems, the thermopower in our devices increases with decreasing temperature below 0.3 K, reaching values in excess of 100 microV/K, thus exceeding the free electron estimate by more than 2 orders of magnitude. With support from a parallel study of the local density of states, we suggest such a phenomenon to be linked to intrinsic localized states and many-body spin correlations in the system.
Goswami
Srijit
S
Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom. sg483@cam.ac.uk
Siegert
Christoph
C
Baenninger
Matthias
M
Pepper
Michael
M
Farrer
Ian
I
Ritchie
David A
DA
Ghosh
Arindam
A