ac Josephson effects in Nb/InAs/Nb junctions with integrated resonators

K. Biedermann; A. Chrestin; T. Matsuyama; U. Merkt

doi:10.1103/PhysRevB.63.144512

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ac Josephson effects in Nb/InAs/Nb junctions with integrated resonators

K. Biedermann, A. Chrestin, T. Matsuyama, U. Merkt

DOI 10.1103/PhysRevB.63.144512 · Physical Review B

T1

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Abstract

Investigations of the ac Josephson effect in Nb/p-type InAs/Nb junctions are presented. Two distinguished features of these devices are an integrated resonator formed by the overlap of two Nb electrodes with an intermediate anodic oxide and their high characteristic voltages IcRN of about 1 mV. Under radio-frequency irradiation, we observe Shapiro steps whose widths follow Bessel functions for high irradiated power. Because of the integrated resonator, self-resonances of the ac Josephson effect can be studied in the current-voltage characteristics. Using a modified resistively shunted junction model which accounts for the presence of the resonator and a nonuniform lateral current distribution, we can describe the magnetic-field dependence of the resonance amplitude. A resonance is also observed when the Josephson frequency is exactly half the lowest resonance frequency, which is beyond the simple model. A possible explanation is provided by a nonsinusoidal current-phase relation established under nonequilibrium conditions.

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