Inhomogeneous superconductivity in organic conductors: the role of disorder and magnetic field

Abstract

Several experimental studies have shown the presence of spatially inhomogeneous phase coexistence of superconducting and non-superconducting domains in low dimensional organic superconductors. The superconducting properties of these systems are found to be strongly dependent on the amount of disorder introduced in the sample regardless of its origin. The suppression of the superconducting transition temperature Tc shows a clear discrepancy with the result expected from the Abrikosov–Gor’kov law giving the behavior of Tc with impurities. On the basis of the time dependent Ginzburg–Landau theory, we derive a model to account for this striking feature of Tc in organic superconductors for different types of disorder by considering the segregated texture of the system. We show that the calculated Tc quantitatively agrees with experiments. We also focus on the effect of superconducting fluctuations on the upper critical fields Hc2 of layered superconductors showing slab structure where superconducting domains are sandwiched by non-superconducting regions. We found that Hc2 may be strongly enhanced by such fluctuations.