Microwave properties of DyBa_2Cu_3O_(7-x) monodomains and related compounds in magnetic fields

TL;DR

This study investigates the microwave surface resistance of a DyBa2Cu3O7-x single domain in magnetic fields, revealing fluxon dynamics and vortex properties consistent with high-temperature superconductor behavior.

Contribution

First detailed microwave characterization of a DyBa2Cu3O7-x single domain, analyzing fluxon motion and vortex parameters in magnetic fields.

Findings

Surface resistance exhibits a square-root dependence on magnetic field.

Estimated London penetration depth at zero temperature is 165 nm.

Vortex viscosity at zero temperature is 3×10^{-7} N·s/m^2.

Abstract

We present a microwave characterization of a DyBa$_{2}$Cu$_{3}$O$_{7-x}$ single domain, grown by the top-seeded melt-textured technique. We report the (a,b) plane field-induced surface resistance, $\Delta R_s(H)$, at 48.3 GHz, measured by means of a cylindrical metal cavity in the end-wall-replacement configuration. Changes in the cavity quality factor Q against the applied magnetic field yield $\Delta R_s(H)$ at fixed temperatures. The temperature range [70 K ; T_c] was explored. The magnetic field $\mu_0 H <$ 0.8 T was applied along the c axis. The field dependence of $\Delta R_s(H)$ does not exhibit the steep, step-like increase at low fields typical of weak-links. This result indicates the single-domain character of the sample under investigation. $\Delta R_s(H)$ exhibits a nearly square-root dependence on H, as expected for fluxon motion. From the analysis of the data in terms of motion of Abrikosov vortices we estimate the temperature dependences of the London penetration depth $\lambda$ and the vortex viscosity $\eta$, and their zero-temperature values $\lambda(0)=$165 nm and $\eta(0)=$ 3 10$^{-7}$ Nsm$^{-2}$, which are found in excellent agreement with reported data in YBa$_{2}$Cu$_{3}$O$_{7-x}$ single crystals. Comparison of microwave properties with those of related samples indicate the need for reporting data as a function of T/T_c in order to obtain universal laws.