Gigantic plasmon resonance effects on magneto-optical activity of molecularly thin ferromagnets near gold surfaces
Abstract
We report on a new magneto-plasmonic material consisting of 1 nm thick ferromagnetic nanosheets and Au nanoparticles. The magnetooptical (MO) Kerr spectra of Ti0.8Co0.2O2 nanosheets near Au surfaces showed a gigantic MO response (similar to 10(6) deg cm(-1)) in the visible wavelength region (380-600 nm), not present in Ti0.8Co0.2O2 nanosheets on a bare glass substrate.
The observed peaks correspond to intrinsic d-d* electronic transitions in Ti0.8Co0.2O2 and are consistent with the near-field enhancement of the MO response resulting from the spectral overlap of the surface-plasmon-resonance (SPR) in the Au surface with the electronic transitions in Ti0.8Co0.2O2. Similar SPR effects were also achieved in ferromagnetic nanosheet/Au with different compositions and with different separation distances (<5 nm).
This demonstration of SPR-enhanced magneto-optics in the ferromagnetic/plasmonic nanosystem may enable designing of nanoarchitectures for miniaturized high-performance MO devices and for remote sensing and imaging of magnetic fields.