Decay Rate of Magnetic Dipoles near Non-magnetic Nanostructures

TL;DR

This paper introduces a theoretical and numerical framework to analyze and optimize the decay rates of magnetic dipoles near non-magnetic nanostructures, enabling design of structures that enhance magnetic transition decay.

Contribution

It presents a novel mixed field-susceptibility formalism and a numerical method for predicting magnetic dipole decay near arbitrary nanostructures, coupled with an optimization algorithm for structure design.

Findings

Analytical expressions for decay rates in simple cases.

Numerical predictions for complex nanostructure geometries.

Optimized structures that maximize magnetic decay rates.

Abstract

In this article, we propose a concise theoretical framework based on mixed field-susceptibilities to describe the decay of magnetic dipoles induced by non--magnetic nanostructures. This approach is first illustrated in simple cases in which analytical expressions of the decay rate can be obtained. We then show that a more refined numerical implementation of this formalism involving a volume discretization and the computation of a generalized propagator can predict the dynamics of magnetic dipoles in the vicinity of nanostructures of arbitrary geometries. We finally demonstrate the versatility of this numerical method by coupling it to an evolutionary optimization algorithm. In this way we predict a structure geometry which maximally promotes the decay of magnetic transitions with respect to electric emitters.