Mean-Field Theory for the Spin-Triplet Exciton Liquid in Quantum Wells

Using a mean-field theory, we study the possible existence of a spin-triplet intersubband exciton liquid ground state in semiconductor quantum well systems as a function of the electronic density and the strength of the intersubband Coulomb interaction matrix element at low temperatures. We find the excitonic phase to be stable over a large region of parameter space, and our calculated critical temperatures are attainable experimentally. In addition, we find that the transition to the excitonic phase can be either first- or second-order at zero temperature.