Conductance characteristics between a normal metal and a two-dimensional Fulde-Ferrell-Larkin-Ovchinnikov superconductor

The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state has received renewed interest recently due to the experimental indication of its presence in CeCoIn$_{5}$. In this work we explore the possibility of detecting the phase structure of the order parameter directly using conductance spectroscopy through micro-constrictions, which probes the phase sensitive surface Andreev bound states of $d$-wave superconductors. We employ the Blonder-Tinkham-Klapwijk formalism to calculate the conductance characteristics between a normal metal and a 2-dimensional $s$- or $d$-wave superconductor in the Fulde-Ferrell state, for all barrier parameter $z$ from the point contact limit ($z$=0) to the tunneling limit (z$\gg $1). We find that the zero-bias conductance peak due to these surface Andreev bound states observed in the uniform $d$-wave superconductor is split and shifted in the Fulde-Ferrell state. This work was supported by NSF grant No. DMR-0225698, NSERC, CFI/OIT, MMO/OCE and CIAR. Reference: cond-mat/0510717.