Rapid Faraday Rotation on ε-Iron Oxide Magnetic Nanoparticles by Visible and Terahertz Pulsed Light

Area of Science:

• Spin chemistry
• Optical materials science
• Nanomagnetism

Background:

• Light- or electromagnetic wave-responsive magnetism is a key area in spin chemistry and optical materials science.
• Developing materials with controllable magnetic properties via external stimuli is crucial for next-generation technologies.

Purpose of the Study:

• To investigate light-induced magnetization reversal and ultrafast magnetooptical effects in ε-iron oxide-based magnetic nanomaterials.
• To explore the potential applications of these materials in high-density magnetic memory and high-speed magnetic devices.

Main Methods:

• Chemical synthesis of gallium-titanium-cobalt-substituted ε-Fe2O3 (GTC-ε-Fe2O3) films and ε-Fe2O3 nanoparticles.
• Irradiation with visible-light pulsed laser and terahertz (THz) pulsed laser.
• Theoretical demonstration using stochastic Landau-Lifshitz-Gilbert calculations.

Main Results:

• Visible-light pulsed laser irradiation induced magnetization reversal in GTC-ε-Fe2O3 films, switching the Faraday effect sign.
• Pulsed THz light irradiation on ε-Fe2O3 films resulted in an ultrafast Faraday rotation within 400 fs.
• Stochastic Landau-Lifshitz-Gilbert calculations validated the observed ultrafast magnetooptical dynamics.

Conclusions:

• ε-iron oxide magnetic nanomaterials demonstrate significant light-responsive magnetic properties.
• These materials show promise for applications in high-density magnetic memory media and high-speed magnetic circuit devices.