Effects of the paramagnetic depairing on structural transitions between vortex lattices of a quasi two dimensional d-wave superconductor are examined. It is found that, in systems with Maki parameter $\alpha_{ \rm M}$ of order unity, a square lattice induced by a d-wave pairing is destabilized with { \it increasing} fields, and that a reentrant rhombic lattice occurs in higher fields. Further, a weak Fermi surface anisotropy competitive with the pairing symmetry induces another structural transition near $H_{ c2}$. These results are consistent with the structure changes of the vortex lattice in CeCoIn$_5$ in ${ \bf H} \parallel c$ determined from recent neutron scattering data.
Categories: cond-mat.supr-con