Observation of geometry-dependent conductivity in two-dimensional electron systems
Physical Review B - Condensed Matter and Materials Physics
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Backes, D., Hall, R., Pepper, M., Beere, H., Ritchie, D., & Narayan, V. (2015). Observation of geometry-dependent conductivity in two-dimensional electron systems. Physical Review B - Condensed Matter and Materials Physics, 92 (23)https://doi.org/10.1103/PhysRevB.92.235427
© 2015 American Physical Society. We report electrical conductivity σ measurements on a range of two-dimensional electron gases (2DEGs) of varying linear extent. Intriguingly, at low temperatures (T) and low carrier density (ns) we find the behavior to be consistent with σ∼Lα, where L is the length of the 2DEG along the direction of transport. Importantly, such scale-dependent behavior is precisely in accordance with the scaling hypothesis of localization [Abrahams, Phys. Rev. Lett. 42, 673 (1979)PRLTAO0031-900710.1103/PhysRevLett.42.673] which dictates that in systems where the electronic wave function ξ is localized, σ is not a material-specific parameter but depends on the system dimensions. From our data we are able to construct the "β function" ≡(h/e2)dlnσ/dlnL and show this to be strongly consistent with theoretically predicted limiting values. These results suggest, remarkably, that the electrons in the studied 2DEGs preserve phase coherence over lengths ∼10μm. This suggests the utility of the 2DEGs studied towards applications in quantum information as well as towards fundamental investigations into many-body localized phases.
We acknowledge funding from the Leverhulme Trust, UK and the Engineering and Physical Sciences Research Council (EPSRC), UK.
UNIVERSITY COLLEGE LONDON (FB EPSRC) (EP/K004077/1)
External DOI: https://doi.org/10.1103/PhysRevB.92.235427
This record's URL: https://www.repository.cam.ac.uk/handle/1810/252559