Microwave properties of YBa$_2$Cu$_3$O$_{7-\delta}$ films with BaZrO$_3$ nanoinclusions

TL;DR

This study investigates how BaZrO$_3$ nanoinclusions in YBa$_2$Cu$_3$O$_{7- heta}$ films affect microwave surface impedance, revealing enhanced vortex pinning within grains despite broadened transition features.

Contribution

It introduces BZO nanoinclusions into YBCO films and demonstrates their significant impact on intragrain vortex pinning at microwave frequencies.

Findings

Enhanced vortex pinning due to BZO nanoinclusions.

Broadening of the superconducting transition in zero field.

Large pinning frequency indicating strong intragrain pinning.

Abstract

We present measurements of the microwave complex surface impedance at 47.7 GHz in YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) films deposited by pulsed laser deposition with the explicit goal to introduce BaZrO$_3$ (BZO) nanoinclusions. Composite targets obtained by addition of BZO powder in molar percents ranging from 2.5 to 7 mol.% have been prepared and characterized. Measurements of the microwave surface impedance indicate a broadened transition in zero field, however compensated by a very large pinning frequency, indicating that while intergrain properties are still to be optimized the effect of nanometric inclusions substantially enhances the intragrain vortex pinning.