Plasmon-Induced Optical Magnetism in an Ultrathin Metal Nanosphere-Based Dimer-on-Film Nanocavity

Yongjun Meng, Qiang Zhang, Dangyuan Lei, Yonglong Li, Siqi Li, Zhenzhen Liu, Wei Xie, Chi Wah Leung

Research output: Journal article publicationJournal articleAcademic researchpeer-review

13 Citations (Scopus)


Recently, plasmon-induced optical magnetism has attracted much research interest in nanophotonics and plasmonics due to intriguing applications in optical metamaterials, and ultrasensitive plasmonic nano-metrology, among many others. Here, a strong in-plane magnetic dipolar resonance in an ultrathin plasmonic nanocavity consisting of a silica-coated gold nanosphere dimer coupled to a gold thin film is observed experimentally and explained theoretically. Multipolar expansion and numerical simulation disclose that such magnetic resonance is induced by a displacement current loop circulating around a nanometer thick triangular region in the cavity. The spectral response and radiation polarization of the magnetic mode are “visualized” by using a polarization-resolved dark-field imaging system at the single-particle level. The resonance responses of this magnetic mode highly depends on cavity gap thickness, nanosphere dimension, and the incident angle, allowing straightforward resonance tuning from the visible to near-infrared region and thus opening up a new avenue for magnetic resonance-enhanced nonlinear optics and chiral optics.

Original languageEnglish
Article number2000068
JournalLaser and Photonics Reviews
Issue number9
Publication statusPublished - 1 Sep 2020


  • dimer-on-film
  • magnetic resonance
  • multipolar expansion
  • optical magnetism
  • plasmonic nanocavity

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics


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