Surface Impedance Measurements on Nb<inline-formula> <tex-math notation="LaTeX">$_{3}$</tex-math> </inline-formula>Sn in High Magnetic Fields

Abstract

Nb 3 Sn is a superconductor of great relevance for perspective RF applications. We present for the first time surface impedance (Zs) measurements at 15 GHz and low RF field amplitude on Nb 3 Sn in high magnetic fields up to 12 T, with the aim of increasing the knowledge of Nb 3 Sn behavior in such conditions. Zs is a fundamental material parameter that directly gives useful information about the dissipative and reactive phenomena when the superconductor is subjected to high-frequency excitations. Therefore, we present an analysis of the measured Zs with the aim of extracting interesting data about pinning in Nb 3 Sn at high frequencies. From Zs we extract the vortex motion complex resistivity to obtain the r-parameter and the depinning frequency νp in high magnetic fields. The comparison of the results with the literature shows that the measured νp on bulk Nb 3 Sn is several times greater than that of pure Nb. This demonstrates how Nb 3 Sn can be a good candidate for RF technological applications, also in high magnetic fields.Index Terms-High magnetic fields, microwave, Nb 3 Sn, depinning frequency, surface impedance.

Vortex Dynamics and Dissipation under High-Amplitude Microwave Drive

“…Initial studies on type-II superconducting films [13] brought about the development of models to describe the vortex-surface-resistance dependence on the frequency [14,15]. Since then, several other studies have investigated the microwave behavior of conventional superconductors [16][17][18][19], cuprates [20][21][22], and iron-based superconductors [23][24][25] in the presence of vortices. In parallel, many theoretical works allow us to describe the expected penetration depth change due to vortex oscillation [26], the vortex-surface-impedance-temperature dependence in high-T c superconductors [27], and the precise electrodynamics of vortex lattices in the mixed state [28].…”

Impact of the superconductors properties on the measurement sensitivity of resonant-based axion detectors

“…The Nb 3 Sn, YBCO and FeSeTe samples were studied through the measurement technique based on the use of the dielectric loaded resonator described and optimized in [34,35,36,37]. In particular the analysis of the vortex motion parameters in Nb 3 Sn was reported in [13,38]. The microwave surface impedance analysis of FeSeTe was detailed in [26,39,40], while the YBCO measurements in high magnetic fields were presented in [41].…”

Challenging microwave resonant measurement techniques for conducting material characterization

“…As shown in figures 8 and 11, a thin SC film in a static magnetic field easily exhibits large surface resistance. Bulk Nb 3 Sn platelet shows R s ∼ 40 mΩ at only 6 K and 4 T, reaching R s ∼ 60 mΩ at the same temperature and 12 T [69]. Thus, the use of twin samples is not always convenient in terms of sensitivity, also at low temperature.…”