Rapid Faraday Rotation on ε‑Iron Oxide Magnetic Nanoparticles by Visible and Terahertz Pulsed Light
mediaposted on 14.01.2019, 20:16 by Shin-ichi Ohkoshi, Kenta Imoto, Asuka Namai, Marie Yoshikiyo, Seiji Miyashita, Hongsong Qiu, Shodai Kimoto, Kosaku Kato, Makoto Nakajima
Light- or electromagnetic wave-responsive magnetism is an attractive issue in spin chemistry and optical materials science. Herein we show the magnetization reversal induced by visible-light pulsed laser and the ultrafast dynamic magnetooptical effect caused by terahertz (THz) pulsed laser irradiation onto chemically synthesized magnetic films based on gallium–titanium–cobalt-substituted ε-Fe2O3 (GTC-ε-Fe2O3) and ε-Fe2O3 nanoparticles. Visible-light pulsed laser irradiation switches the sign of the Faraday effect in GTC-ε-Fe2O3 films. On the other hand, irradiating the ε-Fe2O3 film with pulsed THz light induces an ultrafast Faraday rotation in an extremely short time of 400 fs. The time evolution dynamics of these ultrafast magnetooptical effects are theoretically demonstrated by stochastic Landau–Lifshitz–Gilbert calculations of a nanoparticle model that considers all motions of the individual spins. These ε-iron oxide magnetic nanomaterials are expected to contribute to high-density magnetic memory media or high-speed operation circuit magnetic devices.
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materials scienceRapid Faraday Rotationmagnetoε- iron oxidememory mediaTerahertz Pulsed Light Lightε- Fe 2 O 3 filmultrafast Faraday rotationGTC -ε-Fe 2 O 3laser irradiation switcheselectromagnetic wave-responsive magnetismGTC -ε-Fe 2 O 3 filmsmagnetization reversalTHz lightε- Fe 2 O 3 nanoparticles400 fsFaraday effectoperation circuittime evolution dynamicsnanoparticle modellaser irradiation