Cavity and background oscillations in Intrinsic Josephson Junctions

TL;DR

This paper simulates the current-voltage characteristics of Intrinsic Josephson Junctions, revealing cavity resonances, standing wave patterns, and nonlinear background modes consistent with experimental observations.

Contribution

It provides a detailed simulation of phase dynamics and resonance phenomena in IJJs, highlighting the role of background modes and static kink configurations.

Findings

Voltage jumps at cavity resonance conditions

Presence of higher harmonics up to fifth order

Relation between static kinks and background mode oscillations

Abstract

Starting with zero initial conditions we simulate the current-voltage characteristics (CVCs) of Intrinsic Josephson Junctions (IJJ) for parameters close to that of the BSCCO mesas. The simulation shows a regular pattern with voltage jumps at voltages satisfying the cavity resonance conditions. The calculated emission has peaks at every voltage jump. Analyzing the phases we observe a two-dimensional standing wave pattern with a kink configuration as their static part. Depending on the kink configuration and the bias current, the kink amplitudes may differ from $\pi$ . By means of Fast Fourier Transform (FFT) we show that the frequencies excellently satisfy the ac Josephson relation as in the real experiments. Integer higher harmonics up to fifth order are also observed. Calculated amplitude maps for the frequencies achieved and their harmonics demonstrate that together with cavity modes there exist nonlinear background modes. Direct observation of the phase dynamics shows a relation between oscillations of the background modes and the static kink configuration: opposite static kinks in different junctions correspond to opposite ($\pi$-shifted) oscillations of the background modes.