Evidence of novel quasiparticles in a strongly interacting two-dimensional electron system: giant thermopower and metallic behaviour

Narayan, V and Pepper, M and Griffths, J and Beere, H and Sfigakis, F and Jones, G and Ritchie, D and Ghosh, A (2013) Evidence of novel quasiparticles in a strongly interacting two-dimensional electron system: giant thermopower and metallic behaviour. In: Journal of Low Temperature Physics, 171 (5-6). pp. 626-631.

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Abstract

We report thermopower (S) and electrical resistivity (rho (2DES) ) measurements in low-density (10(14) m(-2)), mesoscopic two-dimensional electron systems (2DESs) in GaAs/AlGaAs heterostructures at sub-Kelvin temperatures. We observe at temperatures a parts per thousand(2)0.7 K a linearly growing S as a function of temperature indicating metal-like behaviour. Interestingly this metallicity is not Drude-like, showing several unusual characteristics: (i) the magnitude of S exceeds the Mott prediction valid for non-interacting metallic 2DESs at similar carrier densities by over two orders of magnitude; and (ii) rho (2DES) in this regime is two orders of magnitude greater than the quantum of resistance h/e (2) and shows very little temperature-dependence. We provide evidence suggesting that these observations arise due to the formation of novel quasiparticles in the 2DES that are not electron-like. Finally, rho (2DES) and S show an intriguing decoupling in their density-dependence, the latter showing striking oscillations and even sign changes that are completely absent in the resistivity.

Item Type:	Journal Article
Publication:	Journal of Low Temperature Physics
Publisher:	Springer
Additional Information:	Copyright of this article belongs to Springer.
Keywords:	Thermopower; 2D Metallicity
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	11 Jun 2013 08:04
Last Modified:	11 Jun 2013 08:04
URI:	http://eprints.iisc.ac.in/id/eprint/46631

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