title: Nanorod Surface Plasmon Enhancement of Laser-Induced Ultrafast Demagnetization.
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/cm(2) 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.
authors.affiliation: Department of Physics and Astronomy, University of Victoria, Victoria V8P 5C2, Canada.
authors.forename: Haitian
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Electrical and Computer Engineering, University of Victoria, Victoria V8P 5C2, Canada.
authors.forename: Ghazal
authors.initials: G
authors.lastname: Hajisalem
authors.affiliation: Department of Physics and Astronomy, University of Victoria, Victoria V8P 5C2, Canada.
authors.forename: Geoffrey M
authors.initials: GM
authors.lastname: Steeves
authors.affiliation: Department of Electrical and Computer Engineering, University of Victoria, Victoria V8P 5C2, Canada.
authors.forename: Reuven
authors.initials: R
authors.lastname: Gordon
authors.affiliation: Department of Physics and Astronomy, University of Victoria, Victoria V8P 5C2, Canada.
authors.forename: Byoung C
authors.initials: BC
authors.lastname: Choi