Superconducting stripline model of intergranular flux penetration

Abstract

A stripline model is successfully applied to an ani;sis of the surface impedance of a granular superconductor. When the core of the stripline is a resistively shunted Josephson junction, the surface resistance increases with the square of the frequency. A dc magnetic field increases the Josephson inductivity, leading to increased surface resistance and flux penetration. Critical flux penetration of the granular surfaces bordering the junction leads to critical behavior of the stripline. At high power level, a dc magnetic field similarly increases the Josephson inductivity with further increase in surface impedance.

Microwave Surface Impedance and Complex Conductivity of High-T c Single Crystals: Current State and Unsolved Problems

“…In developing the traditional approach to the problem, which attributed the residual surface resistance to various imperfections of the surface, the researchers took account of the losses due to weak links [28][29][30], twinning planes 30,31 , clusters with normal conductivity 32 , etc. Numerical estimates, however, indicate that the contribution of these mechanisms to the residual surface resistance is much smaller than R res measured in HTSC materials.…”