  We analyze the mean-field yrast spectrum of a two-component Bose gas in the
ring geometry with arbitrary interaction asymmetry. Of particular interest is
the possibility that the yrast spectrum develops local minima at which
persistent superfluid flow can occur. By analyzing the mean-field energy
functional, we show that local minima can be found at plane-wave states and
arise when the system parameters satisfy certain inequalities. We then go on to
show that these plane-wave states can be yrast states even when the yrast
spectrum no longer exhibits a local minimum. Finally, we obtain conditions
which establish when the plane-wave states cease to be yrast states. Specific
examples illustrating the roles played by the various interaction asymmetries
are presented.
