  We study the interplay of dipole-dipole interaction and optical lattice (OL)
potential of varying depths on the formation and dynamics of vortices in
rotating dipolar Bose-Einstein condensates. By numerically solving the
time-dependent quasi-two dimensional Gross-Pitaevskii equation, we analyse the
consequence of dipole-dipole interaction on vortex nucleation, vortex
structure, critical rotation frequency and number of vortices for a range of OL
depths. Rapid creation of vortices has been observed due to supplementary
symmetry breaking provided by the OL in addition to the dipolar interaction.
Also the critical rotation frequency decreases with an increase in the depth of
the OL. Further, at lower rotation frequencies the number of vortices increases
on increasing the depth of OL while it decreases at higher rotation
frequencies. This variation in the number of vortices has been confirmed by
calculating the rms radius, which shrinks in deep optical lattice at higher
rotation frequencies.
