Weakly interacting Bose mixtures at finite temperature

•Phase diagrams of BEC mixtures at finite temperature applicable to the experimental setup.•Full phase segregation turns out to be impossible at finite temperature.•Upon increasing temperature mixing of condensates is suppressed.

Motivated by the recent experiments on Bose–Einstein mixtures with tunable interactions we study repulsive weakly interacting Bose mixtures at finite temperature. We obtain phase diagrams using Hartree–Fock theory which are directly applicable to experimentally trapped systems. Almost all features of the diagrams can be characterized using simple physical insights. Our work reveals two surprising effects which are dissimilar to a system at zero temperature. First of all, no pure phases exist, that is, at each point in the trap, particles of both species are always present. Second, even for very weak interspecies repulsion when full mixing is expected, condensate particles of both species may be present in a trap without them being mixed.