Chiromagnetic Plasmonic Nanoassemblies with Magnetic Field Modulated Chiral Activity

Area of Science:

• Plasmonics and Nanotechnology
• Chiroptical Materials Science

Background:

• Chiral plasmonic nanoassemblies show promise in sensing, nanophotonics, and biomedical fields.
• Current methods for modulating optical chirality involve irreversible chemical or material changes.
• Real-time, reversible control of optical activity via physical methods remains a significant challenge.

Purpose of the Study:

• To demonstrate directionally and reversibly switching optical chirality in magneto-plasmonic nanoassemblies.
• To explore the application of external magnetic fields for modulating chiroptical properties.
• To investigate the potential of magnetic field-regulated chirality for advanced applications.

Main Methods:

• Fabrication of gold-magnetic nanoparticle core-satellite (Au@Fe3O4) nanostructures.
• Application of external magnetic fields to induce and modulate optical chirality.
• Measurement of circular dichroism signals to quantify chiral activity.

Main Results:

• Au@Fe3O4 nanostructures exhibited chiral activity in the UV-visible range.
• Circular dichroism signal increased 12-fold under an applied magnetic field.
• Chiral signal was reversibly switched by altering the magnetic field direction.

Conclusions:

• External magnetic fields enable real-time, reversible control of optical chirality in magneto-plasmonic nanoassemblies.
• Magnetic dipole moments significantly contribute to the observed magnetic field-modulated polarization rotation.
• This technology holds potential for photonic devices, information communication, and chiral metamaterials.