Fig. 1: Josephson harmonics are relevant for the CφR of tunnel junctions.
From: Observation of Josephson harmonics in tunnel junctions
The nonlinear CφR is the fingerprint of a JJ, which relates the supercurrent I(φ) to the phase φ (inset). For tunnel JJs, the CφR has been considered to be purely sinusoidal (dashed grey line; equation (1)), with the maximum given by the critical current Ic. However, as we show in this work, even in tunnel JJs, the underlying microscopic complexity of the charge transport can manifest in the contribution of higher harmonics to the CφR. As an example, the red line shows a CφR consistent with measured data (CD1 of the KIT sample), which includes the harmonics expected from a mesoscopic model assuming an inhomogeneous AlOx barrier. The shaded red area shows the difference from the purely sinusoidal CφR. We provide CφRs for all other measured samples in Supplementary Fig. 7.
