Physics

Nanotechnology

Organic chemistry

Nanostructure

Crystallography

Magnetic field

Astronomy

Circular dichroism

Chirality (physics)

Paramagnetism

Physical chemistry

Circular polarization

Nanoparticle

Chemical physics

Nambu–Jona-Lasinio model

Chemistry

Materials science

Magnetism

Polarization (electrochemistry)

Condensed matter physics

Chiral symmetry

Spectral line

Quantum mechanics

Optical rotation

Magnetic circular dichroism

Quark

Science

Chiral inorganic nanostructures have high circular dichroism, but real-time control of their optical activity has so far been achieved only by irreversible chemical changes. Field modulation is a far more desirable path to chiroptical devices. We hypothesized that magnetic field modulation can be attained for chiral nanostructures with large contributions of the magnetic transition dipole moments to polarization rotation. We found that dispersions and gels of paramagnetic Co3O4 nanoparticles with chiral distortions of the crystal lattices exhibited chiroptical activity in the visible range that was 10 times as strong as that of nonparamagnetic nanoparticles of comparable size. Transparency of the nanoparticle gels to circularly polarized light beams in the ultraviolet range was reversibly modulated by magnetic fields. These phenomena were also observed for other nanoscale metal oxides with lattice distortions from imprinted amino acids and other chiral ligands. The large family of chiral ceramic nanostructures and gels can be pivotal for new technologies and knowledge at the nexus of chirality and magnetism.

Chiromagnetic nanoparticles and gels