  It is shown that the interface in a two-component Bose-Einstein condensate
(BEC) in which one component exhibits a dipole-dipole interaction spontaneously
forms patterns similar to those formed in a magnetic liquid subject to a
magnetic field. A hexagonal pattern, hysteretic behavior, and soliton-like
structure are numerically demonstrated. A phenomenon similar to the
labyrinthine instability is also found. These phenomena may be realized using a
52Cr BEC. The periodic density modulation in the superfluid ground state offers
evidence of supersolidity.
