# Non-negligible magnetic dipole scattering from metallic nanowire for ultrasensitive deflection sensing

## TL;DR

This paper demonstrates that metallic nanowires exhibit significant magnetic dipole scattering, enabling highly sensitive deflection sensing by encoding nanowire deflections into far-field scattering patterns, surpassing dielectric counterparts.

## Contribution

It reveals the importance of magnetic dipole contributions in metallic nanowire scattering, enabling unidirectional far-field scattering for ultrasensitive deflection detection.

## Key findings

- Magnetic dipole effects enable unidirectional scattering.
- Deflection information is encoded in far-field scattering.
- Enhanced sensitivity compared to dielectric nanowires.

## Abstract

It is generally believed that when a single metallic nanowire is sufficiently small, it scatters like a point electric dipole. We show theoretically when a metallic nanowire is placed inside specially designed beams, the non-negligible magnetic dipole contribution along with the electric dipole resonance can lead to unidirectional scattering in the far-field, fulfilling Kerker's condition. Remarkably, this far-field unidirectional scattering encodes information that is highly dependent on the nanowire's deflection at a scale much smaller than the wavelength. The special role of small but non-negligible magnetic response and plasmonic resonance are highlighted for this extreme sensitivity as compared with the dielectric counterpart. Effects such as scattering efficiency and shape of the nanowire's cross section are also discussed.