Correlated states of electrons in two dimension

Lead Research Organisation: University of Oxford
Department Name: Oxford Physics

Abstract

Electronic systems in two dimension are in some sense a paradigm for undersanding physics in three dimensions. But in other senses new physics can emerge which is completely different due to the reduced dimensionality. This work will examine several sysems of correlated electronic systems in two dimensions where both experiment and theory have left outstanding fundamental questions to be solved. The two main directions we will pursue in the immeidate future are:

(1) Duality of Dirac and Chern-Simons fermion description of fractional quantum Hall states. The HLR theory of the nu=1/2 fermi liquid has given a remarkably successful description of the half-filled Landau level, and the fractional quantum Hall states nearby. In recent years, however, this picture has been challenged by a different picture which starts from a Dirac spectrum. In many ways these two theories give the same experimental predictions. However, it seems possible that the two theories predict very subtle differences. It is an important open question as to whether these two approaches are equivalent or not. This is the simplest example of a huge family of nontrivial dualities which have been conjectured recently - sorting out this issue is of enormous fundamental importance.

(2) Transport in bilayer graphene. Although this system has been studied for a decade or more, new, extremely clean experiments have shown some surprsing results which cannot be fully understood within any existing theory. In particular, understanding the charge and heat transport at overall neutrality remains an open and exciting problem.

This work falls into the EPSRC reseach area "condensed matter physics" and the Grand Challenge areas Emergence and Physics Far from Equilibrium and also Quantum Physics for New Quantum Technologies. Currently there are no companies involved in this work (although I sometimes colalborate with microsoft and it is possible that this work will involve collaboration with microsoft). We envision collaboration with Dung Nguyen Xuan, a postdoc at Oxford funded by EPSRC EP/N01930X/1 . There is some chance of collaboration with Dima Abanin a professor in Geneva.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509711/1 01/10/2016 30/09/2021
1947374 Studentship EP/N509711/1 01/10/2017 31/03/2121 Glenn Wagner
 
Description We discovered that electrons in bilayer graphene --- a particular two-dimensional material --- can behave in the same way as a fluid such as water. This is unusual, in an ordinary metal the electrons are constantly scattering off impurities. On the other hand, bilayer graphene is extremely clean and therefore the electrons are mainly talking to each other and this leads to the collective flow of electrons as in a fluid. We found signatures of this so-called hydrodynamic transport that can be observed in experiments.
Exploitation Route We hope that experimental groups at other universities will attempt to look for these signatures of hydrodynamic transport, such as the violation of the Wiedemann-Franz law in bilayer graphene.
Sectors Electronics