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‘Metal’-like transport in high-resistance, high aspect ratio two-dimensional electron gases


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Abstract

We investigate the striking absence of strong localisation observed in mesoscopic two-dimensional electron gases (2DEGs) [1, 2] even when their resistivity ρ >> h/e² . In particular, we try to understand whether this phenomenon originates in quantum many-body effects, or simply percolative transport through a network of electron puddles. To test the latter scenario, we measure the low temperature (low-T) transport properties of long and narrow 2DEG devices in which percolation effects should be heavily suppressed in favour of Coulomb blockade. Strikingly we find no indication of Coulomb blockade and that the high-ρ, low-T transport is exactly similar to that previously reported in mesoscopic 2DEGs with different geometries. Remarkably, we are able to induce a ‘metal’-insulator transition (MIT) by applying a perpendicular magnetic field B. We present a picture within which these observations fit into the more conventional framework of the 2D MIT.

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Keywords

Journal Title

Journal of Physics: Condensed Matter

Conference Name

Journal ISSN

0953-8984
1361-648X

Volume Title

28

Publisher

IOP Publishing
Sponsorship
EPSRC (EP/J003417/1)
UNIVERSITY COLLEGE LONDON (FB EPSRC) (EP/K004077/1)
We acknowledge funding from the Leverhulme Trust, UK and the Engineering and Physical Sciences Research Council (EPSRC), UK.