Thermoelectric and electrical transport in mesoscopic two-dimensional electron gases

Publication date: Available online 21 August 2016 Source:Comptes Rendus Physique Author(s): Vijay Narayan, Michael Pepper, David A. Ritchie We review some of our recent experimental studies on low-carrier concentration, mesoscopic two-dimensional electron gases (m2DEGs). The m2DEGs show a range of striking characteristics, including a complete avoidance of the strongly localised regime even when the electrical resistivity ρ > > h / e 2 , giant thermoelectric response, and an apparent decoupling of charge and thermoelectric transport. We analyse the results and demonstrate that these observations can be explained based on the assumption that the charge carriers retain phase coherence over the m2DEG dimensions. Intriguingly, this would imply phase coherence on lengthscales of up to 10 μm and temperature T up to 10 K, which is significantly greater than conventionally expected in GaAs-based 2DEGs. We critically assess this assumption and explore other possible explanations to the data. Such unprecedentedly large phase coherence lengths open up several possibilities in quantum information and computation schemes.

Source: Comptes Rendus Physique - August 20, 2016 Category: Physics Source Type: research