  We characterize the immiscibility-miscibility transition (IMT) of a
two-component Bose-Einstein condensate (BEC) with dipole-dipole interactions.
In particular, we consider the quasi-two dimensional geometry, where a strong
trapping potential admits only zero-point motion in the trap direction, while
the atoms are more free to move in the transverse directions. We employ the
Bogoliubov treatment of the two-component system to identify both the
well-known long-wavelength IMT in addition to a roton-like IMT, where the
transition occurs at finite-wave number and is reminiscent of the roton
softening in the single component dipolar BEC. Additionally, we verify the
existence of the roton IMT in the fully trapped, finite systems by direct
numerical simulation of the two-component coupled non-local Gross-Pitaevskii
equations.
