Enhancement of the critical temperature in iron-pnictide superconductors by finite size effects

TL;DR

This paper investigates how finite size effects in nanoscale iron-pnictide superconductors can lead to oscillations and enhancements in the critical temperature, supported by theoretical models and potential experimental signatures.

Contribution

It demonstrates that finite size effects can significantly enhance and oscillate the critical temperature in iron-pnictide superconductors at nanoscale dimensions.

Findings

Tc(L) exhibits oscillating behavior with system size L

Substantial Tc enhancement observed at L ~ 10 nm

Differential conductance is highly sensitive to finite size effects

Abstract

Recent experiments have shown that, in agreement with previous theoretical predictions, superconductivity in metallic nanostructures can be enhanced with respect to the bulk limit. Motivated by these results we study finite size effects (FSE) in an iron-pnictide superconductor. For realistic values of the bulk critical temperature Tc ~ 20-50K, we find that, in the nanoscale region L ~ 10 nm, Tc(L) has a complicated oscillating pattern as a function of the system size L. A substantial enhancement of Tc with respect to the bulk limit is observed for different boundary conditions, geometries and two microscopic models of superconductivity. Thermal fluctuations, which break long range order, are still small in this region. Finally we show that the differential conductance, an experimental observable, is also very sensitive to FSE.