Exciton Condensates Through the Years

Event Type: IFIMAColloquium.
Title: Exciton Condensates Through the Years
When: Friday, 24th March, 2023, at 12:00.
Where: Sala de Conferencias, Módulo 00, Facultad de Ciencias, Universidad Autónoma de Madrid.
Speaker: Allan MacDonald, Department of Physics, University of Texas at Austin, Austin, TX, USA.

Excitons are composite bosons formed by pairing electrons and holes in a crystal. The idea that excitons might Bose condense and that condensed excitons might have spectacular electrical properties dates back to the 1960’s but has often been surrounded by controversy. My talk will focus on the important lessons learned about exciton condensates from work on two-dimensional electron systems in the quantum Hall regime, starting around twenty years ago, and on new opportunities [1] to create exciton condensates and engineer their properties created by advances in stacking individual layers of van der Walls materials. I will also discuss the recent observation of dipolar condensates [2] in double bilayer graphene in the absence of a magnetic field, highlighting the unusual connection [3] between electron-hole pairing channels and Dirac point Berry phases in the isolated bilayers.


  1. Strongly correlated excitonic insulator in atomic double layers, Ma L, Nguyen PX, Wang Z, Zeng Y, Watanabe K, Taniguchi T, MacDonald AH, Mak KF, Shan J., Nature. 2021 Oct 28;598(7882):585-9.
  2. Strongly enhanced tunneling at total charge neutrality in double bilayer-graphene-WSe2 heterostructures, G. William Burg et al., Phys. Rev. Lett. 120, 177702 (2018).
  3. Spatially-indirect Exciton Condensate Phases in Double Bilayer Graphene, Jung-Jung Su and A.H. MacDonald, Phys. Rev. B 95, 045416 (2017).

Exciton Condensates Through the Years - Poster

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