Microscopic examination of hot spots giving rise to nonlinearity in superconducting resonators

Cihan Kurter; Alexander P. Zhuravel; Alexey V. Ustinov; Steven M. Anlage

doi:10.1103/PhysRevB.84.104515

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Microscopic examination of hot spots giving rise to nonlinearity in superconducting resonators

Cihan Kurter, Alexander P. Zhuravel, Alexey V. Ustinov, Steven M. Anlage

DOI 10.1103/PhysRevB.84.104515 · Physical Review B

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Abstract

We investigate the microscopic origins of nonlinear rf response in superconducting electromagnetic resonators. Strong nonlinearity appearing in the transmission spectra at high input powers manifests itself through the emergence of jumplike features near the resonant frequency that evolve toward lower quality factor with higher insertion loss as the rf input power is increased. We directly relate these characteristics to the dynamics of localized normal regions (hot spots) caused by microscopic features in the superconducting material making up the resonator. A clear observation of hot-spot formation inside a Nb thin film self-resonant structure is presented by employing the microwave laser scanning microscope, and a direct link between microscopic and macroscopic manifestations of nonlinearity is established.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Nb Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Nb Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown