Optical Manipulation of Magnetism in Iron Oxide Nanoparticles

Optical Manipulation of Magnetism in Iron Oxide Nanoparticles

Scientific Achievement
Magnetization of iron oxide nanoparticles is optically modulated by the interaction between excitons and atomic spins. This interaction reduces the energy barrier (from black to red) and facilitated an optically-driven conversion from ferrimagnetism to superparamagnetism (top-right).  (hi-res image)

Shining light onto iron oxide nanoparticles is shown to change their magnetic properties

Significance and Impact

Optically controlled magnetism in nanoparticles offers a practical interface mechanism for spintronics and photonics devices.

Research Details

– Discovered an unconventional mechanism: optical excitation creates electron-hole pairs that couple to spins. The resulting reduction of the energy barrier then leads to a transition from ferrimagnetism to superparamagnetism.

– Excluded photothermal effects as the source of magnetization change via computational simulation.

– Confirmed the correlation between magnetization and electron-hole pair generation by steady-state and time-resolved  photoluminescence studies.

S. He, J. S. DuChene, J. Qiu, A. A. Puretzky, Z. Gai, and W. D. Wei, "Persistent photomagnetism in superparamagnetic iron oxide nanoparticles," Advanced Electronic Materials (2018).  DOI: 10.1002/aelm.201700661R2

CNMS Researchers