Detection of low-level dissipation and thermal instability in Y Ba₂Cu₃O_{7 − δ}microbridges using low temperature near-field scanning microwave microscopy

Abstract

Near-field scanning microwave microscopy (NSMM) was combined with electrical transport measurements to detect the dynamic evolution of low-level dissipation and thermal instability in YBa 2 Cu 3 O 7−δ microbridges in the superconducting state driven by temperature, applied current and self-heating. High sensitivity NSMM enables quantitative detection of dissipation evolution starting from 3 to 4 orders of magnitude lower than the transport critical current criterion. The nonlinear step-like feature in the dynamic development of dissipation suggests a bi-modal evolution pattern of nucleation of isolated hot spots followed by their spreading/coalescence. A linear behavior prevails near the superconducting-to-normal transition.