Flux distribution in vortex lattice states in d-wave and paramagnetic superconductors

Roles of field-induced antiferromagnetic (AFM) fluctuation in the vortex lattice in d-wave superconductors with strong Pauli paramagnetic depairing (PD) are studied with a focus on the heavy-fermion superconductor CeCoIn5. Based on the Ginzburg-Landau approach, we calculate the field dependence of the vortex lattice form factor (VLFF) which reflects the magnetic flux distribution in the vortex lattice. It is found that, in a magnetic field perpendicular to the two-dimensional plane (H || c), the strong AFM fluctuation near Hc2(0) enhances the VLFF in high fields and that this enhancement is remarkable when the AFM moment is perpendicular to H (m perpendicular H). The obtained result in m perpendicular H well explains an anomalous field dependence of the VLFF obtained in neutron scattering experiments on CeCoIn5, which suggests the necessity of taking account of the AFM fluctuation and the possibility that the configuration m perpendicular H is realized in H || c.