Enhancement of critical current density and vortex activation energy in proton-irradiated Co-doped BaFe2As2

TL;DR

Proton irradiation enhances the critical current density and vortex activation energy in Co-doped BaFe2As2 superconductors by modifying flux pinning and creep properties, as analyzed through various models and experimental methods.

Contribution

This study provides a detailed analysis of how proton irradiation improves flux pinning and critical current density in BaFe2As2, introducing a comprehensive model and experimental validation.

Findings

Proton irradiation doubles the flux creep barrier height.

The critical current density is significantly increased after irradiation.

Flux relaxation rates are reduced, indicating improved vortex pinning.

Abstract

The effect of proton irradiation in Ba(Fe0.93Co0.07)2As2 single crystals is reported. We analyze temperature dependence of current density and normalized flux relaxation rate in the framework of collective creep model. Glassy exponent and barrier height for flux creep are directly determined by Maley's method. Our model functions for barrier height and critical current density in the absence of flux creep are explained by the superposition of \deltaTc- and \deltal-pinning. We also approach true critical current density by means of generalized inversion scheme, and the obtained result is in reasonable agreement with our model function. Proton irradiation effect on temperature dependence of current density and normalized relaxation rate can be summarized as doubling of barrier height at the beginning of flux creep.