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Small Hall, Room 122
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Dipolar excitons are bosons consisting of a paired state of electrons and holes which are spatially separated from each other and interact only via the Coulomb interaction. It has long been predicted that under appropriate conditions they can form a macroscopic condensate, and this has been observed for two-dimensional electron gases in a strong magnetic field. However, this phenomenon has never been observed at zero field. In this talk, we begin with an introduction to the field of dipolar excitons and then describe how charged impurity disorder impacts the formation of such a condensate in double graphene layer systems. We then examine exciton condensation in one-dimensional systems, a concept which appears to be excluded by the Mermin-Wagner theorem. However, we show that the inclusion of an inter-layer single particle hopping process breaks the conditions for the theorem and allows off-diagonal long range order in the condensate channel.

References:
D.S.L. Abergel, R. Sensarma, and S. Das Sarma, Phys. Rev. B 86,
155447(R) (2012).
D.S.L. Abergel, M. Rodriguez-Vega, E. Rossi, and S. Das Sarma, Phys.
Rev. B 88, 235402 (2013).
D.S.L. Abergel, Appl. Phys. Lett. 106, 213103 (2015).