Frequency Domain Simulations of Charge-Density-Wave Strains: Comparison with Electro-Optic Measurements

TL;DR

This study models charge-density-wave strain responses to alternating currents using numerical simulations, revealing spatial and current-dependent dynamics consistent with experimental electro-optic measurements.

Contribution

It introduces a detailed numerical analysis of charge-density-wave strain dynamics, comparing model predictions with experimental data to elucidate phase-slip effects and contact pinning.

Findings

Delay time decreases near contacts and with higher current.

Strain relaxation times are reduced at higher phase-slip rates.

Pinning at contacts accelerates strain changes between contacts.

Abstract

We have studied changes in charge-density-wave strain under application of square-wave currents of variable amplitude and frequency by numerically solving the phase-slip augmented diffusion model introduced by Adelman et al (Phys. Rev. B 53, 1833 (1996)). The frequency dependence of the strain, at each position and amplitude, was fit to a modified harmonic oscillator expression, and the position and current dependence of the fitting parameters determined. In particular, the delay time (1/resonant frequency) vanishes adjacent to the contact and grows with distance from the contact, and both the delay time and relaxation time decrease rapidly with increasing current (and phase-slip rate), as experimentally observed in the electro-optic response of blue bronze. We have also found that pinning the phase at the contacts causes more rapid changes in strain between the contacts than allowing the phase to flow outside the contacts.