Dephasing time of disordered two-dimensional electron gas in modulated magnetic fields

TL;DR

This paper investigates how the dephasing time of a disordered two-dimensional electron gas depends on magnetic field inhomogeneity, revealing a transition from linear to quadratic dependence and developing a Monte Carlo method to analyze complex modulations.

Contribution

It introduces a semiclassical Monte Carlo algorithm to study dephasing in complex magnetic field modulations and generalizes the linear-quadratic crossover to periodic magnetic fields.

Findings

Dephasing rate is proportional to field amplitude in weak inhomogeneity.

Dephasing rate becomes quadratic in strong inhomogeneity.

Monte Carlo simulations support analytical predictions.

Abstract

The dephasing time of disordered two-dimensional electron gas in a modulated magnetic field is studied. It is shown that in the weak inhomogeneity limit, the dephasing rate is proportional to the field amplitude, while in strong inhomogeneity limit the dependence is quadratic. It is demonstrated that the origin of the dependence of dephasing time on field amplitude lies in the nature of corresponding single-particle motion. A semiclassical Monte Carlo algorithm is developed to study the dephasing time, which is of qualitative nature but efficient in uncovering the dependence of dephasing time on field amplitude for arbitrarily complicated magnetic-field modulation. Computer simulations support analytical results. The crossover from linear to quadratic dependence is then generalized to the situation with magnetic field modulated periodically in one direction with zero mean, and it is argued that this crossover can be expected for a large class of modulated magnetic fields.