The Off-Shell Electromagnetic T-matrix: momentum-dependent scattering from spherical inclusions with both dielectric and magnetic contrast

TL;DR

This paper derives a comprehensive momentum- and frequency-dependent T-matrix for electromagnetic scattering by spherical inclusions with dielectric and magnetic properties, extending previous dielectric-only models and useful for effective-medium theories.

Contribution

It introduces a generalized Mie-type series for the T-matrix that accounts for magnetic effects, unifying dielectric and magnetic scattering in a compact, symmetry-emphasized form.

Findings

Derived a momentum-dependent T-matrix for magnetic and dielectric spheres.

Extended previous dielectric-only models to include magnetic properties.

Achieved partial summation of the Mie series for elastic scattering.

Abstract

The momentum- and frequency-dependent T-matrix operator for the scattering of electromagnetic waves by a dielectric/conducting and para- or diamagnetic sphere is derived as a Mie-type series, and presented in a compact form emphasizing various symmetry properties, notably the unitarity identity. This result extends to magnetic properties one previously obtained for purely dielectric contrasts by other authors. Several situations useful to spatially-dispersive effective-medium approximations to one-body order are examined. Partial summation of the Mie series is achieved in the case of elastic scattering.