Effect of boron doping in the microwave surface resistance of neutron irradiated melt-textured Y_1.6Ba_2.3Cu_3.3O_7-x samples

TL;DR

This study investigates how boron doping and neutron irradiation affect the microwave surface resistance and fluxon dynamics in melt-textured YBCO superconductors, revealing that B_2O_3 enhances defect effectiveness in impeding fluxon motion.

Contribution

It provides a detailed analysis of defect effects and fluxon behavior in doped, irradiated YBCO using adapted Coffey and Clem theory, highlighting the role of B_2O_3 in improving flux pinning.

Findings

B_2O_3 doping up to 0.1 wt% increases defect effectiveness.

Neutron irradiation influences the intergranular properties.

Boron doping enhances flux pinning by defects.

Abstract

We report on the microwave surface resistance of melt-textured Y_1.6Ba_2.3Cu_3.3O_7-x samples, doped with different amount of B_2O_3 and, subsequently, irradiated by thermal neutrons at the fluence of 1.476 \times 10^17 cm^-2. The microwave surface resistance has been measured as a function of temperature and DC magnetic field. The experimental results are quantitatively discussed in the framework of the Coffey and Clem theory, properly adapted to take into account the d-wave nature of cuprate superconductors. By fitting the experimental data at zero DC field, we have highlighted the effects of the induced defects in the general properties of the samples, including the intergranular region. The analysis of the results obtained at high DC fields allowed us to investigate the fluxon dynamics and deduce the depinning frequency; in particular, we have shown that the addition of B_2O_3 up to 0.1 wt% increases the effectiveness of the defects to hinder the fluxon motion induced by the microwave current.