Phase diagram and spectroscopy of Fulde-Ferrell-Larkin-Ovchinnikov states of two-dimensionald-wave superconductors

Abstract

Experimental evidence suggests that the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state may be realized in the unconventional, heavy-fermion superconductor CeCoIn5. We present a self-consistent calculation of the field versus temperature phase diagram and order parameter structures for the FFLO states of quasi-two-dimensional d-wave superconductors. We calculate the spatially nonuniform order parameter, free energy density, and local density of states for magnetic fields parallel to the superconducting planes. We predict that the lower critical magnetic field transition between the spatially uniform and nonuniform FFLO state is second order. We discuss the signatures of the nonuniform FFLO state which should be observable in scanning tunneling microscopy measurements of the local density of states.

Broken Translational and Time-Reversal Symmetry in Unconventional Superconducting Films

“…Note, that this transition occurs below unphysical q x = 0 line (thin dots in Fig. 3), as compared with the FFLO problem [25,26]: there is no first order transition above q x = 0 line in this case -thus the inhomogeneous phase must cover the entire thermodynamically unstable region. Energetically, the state with the modulated amplitude of the OP gains energy compared with the energy of 'uniform' state from the reduction of pairbreaking at the domain walls and the redistribution of the Andreev bound states.…”

Complex-Stripe Phases Induced by Staggered Rashba Spin–Orbit Coupling

“…4(a)], indicating the "quasi-Andreev bound state" in the complex-stripe phase. Indeed, these peaks adiabatically change to the subgap structure due to Andreev bound states in the LO state, 45) with decreasing spin-orbit coupling α. However, the peaks become obscure as the magnetic field increases [ Fig.…”

Spectroscopic signatures of the Larkin-Ovchinnikov state in the conductance characteristics of a normal-metal/superconductor junction

“…27 However, direct evidence for the periodic OP variation is still desirable. [28][29][30][31][32][33] To help identify the FFLO state unambiguously, we previously proposed using conductance spectroscopy of normal-metal (N)/ superconductor (S) junctions as an experimental probe, treating the FF state first as an illustrative case in that work. 34 However, only the spectral characteristics of a momentum-dependent gap due to a single non-zero pairing momentum are discussed there.…”