Fulde-Ferrell state in quasi-two-dimensional superconductors

Publisher Website
Google Scholar
Abstract
Inhomogeneous superconductivity proposed by Fulde and Ferrell (FF state) is studied in a strongly Pauli-limited type-II superconductor with a cylindrical Fermi surface. The phase diagram of the FF state, BCS state, and normal state is obtained. It is found that the FF state is remarkably enhanced owing to the two-dimensional Fermi-surface structure in comparison to the spherical symmetric case. We discuss that the Fermi-surface nesting is also advantageous to the FF state as well as nesting instabilities. Our result obtained in the cylindrical symmetric case is applicable in general to quasi-low-dimensional superconductors in which the nesting is sufficiently incomplete so that the nesting instabilities are suppressed. Relation to the exotic superconductors discovered recently is briefly discussed.