Fulde–Ferrell–Larkin–Ovchinnikov state in d-wave superconductors

Recent reports of anomalous low-temperature properties at high magnetic fields of κ-(BEDT-TFF) 2Cu(NCS) 2 and λ-(BEDTS) 2GaCl 4 have sparked a renewed interest in possible Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) states in d-wave superconductors. In contrast to conventional three-dimensional s-wave superconductors, there is evidence that FFLO states are realizable for quasi-two-dimensional anisotropic superconductors in a magnetic field parallel to the conducting plane. In this paper, the quasiparticle density of states N( E) are studied in two-dimensional d xy -wave and d x 2− y 2 -wave superconductors. The energy dependence of N( E) provides clear signatures of the FFLO state.