Nonlinear Meissner effect in Nb 3 Sn coplanar resonators

• Published in: Physical review research Vol. 4; no. 1
• Main Authors: Makita, J., Sundahl, C., Ciovati, G., Eom, C. B., Gurevich, A.
• Format: Journal Article
• Language: English
• Published: United States American Physical Society 25.02.2022
• ISSN: 2643-1564; 2643-1564
• DOI: 10.1103/PhysRevResearch.4.013156

We investigated the nonlinear Meissner effect (NLME) in Nb3Sn thin-film coplanar resonators by measuring the resonance frequency as a function of a parallel magnetic field at different temperatures. We used low rf power probing in films thinner than the London penetration depth λ(B) to significantly increase the field onset of vortex penetration and measure the NLME under equilibrium conditions. Contrary to the conventional quadratic increase of λ(B) with B expected in s-wave superconductors, we observed a nearly linear increase of the penetration depth with B. We concluded that this behavior of λ(B) is due to weak linked grain boundaries in our polycrystalline Nb3Sn films, which can mimic the NLME expected in a clean d-wave superconductor.