Thermodynamic Model of the Macroscopically Ordered Exciton State

We explain the experimentally observed instability of cold exciton gases and the formation of a macroscopically ordered exciton state in terms of a thermodynamic model accounting for the phase fluctuations of the condensate. We show that the temperature dependence of the exciton energy exhibits fundamental scaling behavior with the signature of the second order phase transition. DOI: 10.1103/PhysRevLett.110.146401