Atomic Bose-Fermi mixed condensates with Boson-Fermion quasi-bound cluster states

Abstract

The boson-fermion atomic bound states (composite fermion) and their roles for the phase structures are studied in a bose-fermi mixed condensate of atomic gas in finite temperature and density. The two-body scattering equation is formulated for a boson-fermion pair in the mixed condensate with the Yamaguchi-type potential. By solving the equation, we evaluate the binding energy of a composite fermion, and show that it has small T-dependence in the physical region, because of the cancellation of the boson- and fermion- statistical factors in the equation. We also calculate the phase structure of the BF mixed condensate under the equilibrium B+F -> BF, and discuss the role of the composite fermions: the competitions between the degenerate state of the composite fermions and the Bose-Einstein condensate (BEC) of isolated bosons. The criterion for the BEC realization is obtained from the algebraically-derived phase diagrams at T=0.