Magnetic Dipole Absorption of Radiation in Small Conducting Particles

TL;DR

This paper provides a theoretical analysis of magnetic dipole absorption in small conducting particles, considering both diffusive and ballistic electron dynamics, across different frequency regimes.

Contribution

It introduces a comprehensive theoretical framework for magnetic dipole absorption in small particles, accounting for arbitrary shapes and electron transport regimes.

Findings

Absorption coefficient is unaffected by  in diffusive case.

In ballistic case, absorption scales as ^2 for low frequencies.

Absorption decreases with frequency when  exceeds .

Abstract

We give a theoretical treatment of magnetic dipole absorption of electromagnetic radiation in small conducting particles, at photon energies which are large compared to the single particle level spacing, and small compared to the plasma frequency. We discuss both diffusive and ballistic electron dynamics for particles of arbitrary shape. The conductivity becomes non-local when the frequency is smaller than the frequency \omega_c characterising the transit of electrons from one side of the particle to the other, but in the diffusive case \omega_c plays no role in determining the absorption coefficient. In the ballistic case, the absorption coefficient is proportional to \omega^2 for \omega << \omega_c, but is a decreasing function of \omega for \omega >> \omega_c.