Modifications of the Meissner screening profile in YBa₂Cu₃O₇₋δ thin films by gold nanoparticles

الأصل · EN

Adding Au nanoparticles to YBa₂Cu₃O₇₋δ thin films leads to an increase of the superconducting transition temperature T c and the critical current density j c. While the higher j c can be understood in terms of a stronger pinning of the flux vortices at the Au nanoparticles, the enhanced T c is still puzzling. In the present study, we determined the microscopic magnetic penetration profiles and the corresponding London penetration depths λ L in the Meissner state of optimally doped YBa₂Cu₃O₇₋δ thin films with and without Au nanoparticles by low-energy muon spin rotation. By Rutherford backscattering spectrometry, we show that the Au nanoparitcles are distributed over the whole thickness of the thin-film samples. The superfluid density n s ∝ 1/λ L² was found to increase in the films containing Au nanoparticles. We attribute this increase of n s to a reduction of the defect density possibly due to defect condensation at the Au nanoparticles.