Large Fluctuations and Singular Behavior of Nonequilibrium Systems

TL;DR

This paper introduces a geometric method to analyze escape dynamics in nonequilibrium systems, identifying conditions under which caustic singularities affect escape trajectories, with applications to magnetic systems without detailed balance.

Contribution

It provides a novel geometric framework for understanding escape phenomena in nonequilibrium systems, especially those lacking detailed balance, and offers criteria for caustic formation.

Findings

Derived a simple condition based on the drift field norm for caustic influence.

Applied the method to nanomagnets with spin transfer torque.

Mapped experimental parameter regions where caustics occur.

Abstract

We present a general geometrical approach to the problem of escape from a metastable state in the presence of noise. The accompanying analysis leads to a simple condition, based on the norm of the drift field, for determining whether caustic singularities alter the escape trajectories when detailed balance is absent. We apply our methods to systems lacking detailed balance, including a nanomagnet with a biaxial magnetic anisotropy and subject to a spin transfer torque. The approach described within allows determination of the regions of experimental parameter space that admit caustics.