Quantum creep and quantum creep transitions in 1D sine-Gordan chains

TL;DR

This study investigates quantum creep phenomena in one-dimensional sine-Gordon chains using path-integral molecular dynamics, revealing transitions from quantum creep to pinning and depinning, influenced by disorder and quantum fluctuations.

Contribution

It introduces a detailed analysis of quantum creep transitions in discrete sine-Gordon chains, highlighting effects of disorder and quantum fluctuations not previously characterized.

Findings

Transition from quantum creep to pinning at specific bead masses.

Identification of a creep to depinning transition driven by external field.

Differential effects of disorder on quantum and classical fluctuations.

Abstract

Discrete sine-Gordon (SG) chains are studied with path-integral molecular dynamics. Chains commensurate with the substrate show the transition from collective quantum creep to pinning at bead masses slightly larger than those predicted from the continuous SG model. Within the creep regime, a field-driven transition from creep to complete depinning is identified. The effects of disorder in the external potential on the chain's dynamics depend on the potential's roughness exponent $H$, i.e., quantum and classical fluctuations affect the current self-correlation functions differently for $H = 1/2$.