Work

Optical trapping with optical magnetic field and photonic Hall effect forces

Year: 2025

Type: article

Abstract: Optical trapping offers robust nanoscale control of matter but, to date, has been dominated by the interaction between a material’s electric polarizability, αe, and the electric part of light, therefore defined by electric-field intensity-gradient forces. Magnetic light-matter interactions, despite their potential to reshape optical trapping research, have remained experimentally unrealized. This paper addresses this long-standing deficiency by realizing optical magnetic field-associated trapping of high-index (i.e., Si) nanoparticles. Experiments, validated by our theoretical framework and Maxwell stress tensor calculations, reveal the essential role of a material’s magnetic polarizability, αm, and electric-magnetic scattering forces arising from the photonic Hall effect. This magnetic contribution allows exploration of stable trapping, distinct from purely electric-field control. Our findings open avenues for nanoparticle manipulation beyond conventional paradigms, enable previously unexamined optical matter formation driven by magnetic interactions, and suggest unexplored N-body effects and symmetry-breaking dynamics in optical matter systems. The authors achieve magnetic trapping at optical frequencies and uncover photonic Hall effect forces by engineering spatially isolated magnetic fields interacting with a single Si nanoparticle at its magnetic dipole resonance.

Source: Nature Communications

DOI: 10.1038/s41467-025-65334-6