Nanorod Surface Plasmon Enhancement of Laser-Induced Ultrafast Demagnetization
Date
2015-10-30
Authors
Xu, Haitian
Hajisalem, Ghazal
Steeves, Geoffrey M.
Gordon, Reuven
Choi, Byoung C.
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Nature: Scientific Reports
Abstract
Ultrafast laser-induced magnetization dynamics in ferromagnetic thin films were measured using a femtosecond Ti:sapphire laser in a pump-probe magneto-optic Kerr effect setup. The effect of plasmon resonance on the transient magnetization was investigated by drop-coating the ferromagnetic films with dimensionally-tuned gold nanorods supporting longitudinal surface plasmon resonance near the central wavelength of the pump laser. With ~4% nanorod areal coverage, we observe a >50% increase in demagnetization signal in nanorod-coated samples at pump fluences on the order of 0.1 mJ/cm2 due to surface plasmon-mediated localized electric-field enhancement, an effect which becomes more significant at higher laser fluences. We were able to qualitatively reproduce the experimental observations using finite-difference time-domain simulations and mean-field theory. This dramatic enhancement of ultrafast laser-induced demagnetization points to possible applications of nanorod-coated thin films in heat-assisted magnetic recording.
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Citation
Xu, H., Hajisalem, G., Steeves, G.M., Gordon, R. & Choi, B.C. (2015). Nanorod surface plasmon enhancement of laser-induced ultrafast demagnetization. Nature: Scientific Reports, 5(15933), 1-6.