Magnetic penetration depth in disordered iron-based superconductors

TL;DR

This paper investigates how disorder affects the London penetration depth in iron-based superconductors using a two-band model, revealing significant effects especially in the coexistence phase of magnetic and superconducting states.

Contribution

It introduces a theoretical framework combining a two-band model with quasiclassical equations to analyze disorder effects on penetration depth in these materials.

Findings

Disorder significantly influences the penetration depth in the coexistence phase.

Analytical expressions for penetration depth are derived for various limits.

Numerical analysis shows doping and temperature dependence of the effects.

Abstract

We study the effect of disorder on the London penetration depth in iron-based superconductors. The theory is based on a two-band model with quasi-two-dimensional Fermi surfaces, which allows for the coexistence region in the phase diagram between magnetic and superconducting states in the presence of intraband and interband scattering. Within the quasiclassical approximation we derive and solve Eilenberger's equations, which include a weak external magnetic field, and provide analytical expressions for the penetration depth in the various limiting cases. A complete numerical analysis of the doping and temperature dependence of the London penetration depth reveals the crucial effect of disorder scattering, which is especially pronounced in the coexistence phase. The experimental implications of our results are discussed.