Magnetic Vortex Dynamics Probed by Time-Resolved Magnetic Helicoidal Dichroism.

Area of Science:

• Magnetism and Spintronics
• Ultrafast Laser Physics
• Materials Science

Background:

• Laser-induced magnetization dynamics are crucial for advanced magnetic applications.
• Controlling spin textures without external fields is a significant challenge.
• Magnetic vortices exhibit complex spin textures sensitive to external stimuli.

Purpose of the Study:

• To investigate the use of ultrashort infrared laser pulses for triggering transient spin texture changes in magnetic vortices.
• To probe laser-induced dynamics using time-resolved magnetic helicoidal dichroism (MHD) and micromagnetic simulations.
• To provide direct evidence of transient spin texture reorganizations and surface spin reversals.

Main Methods:

• Excitation of magnetic vortex dynamics using ultrashort infrared laser pulses.
• Time-resolved magnetic helicoidal dichroism (MHD) in resonant extreme ultraviolet scattering for probing.
• Micromagnetic simulations to support experimental observations and analyze spin textures.

Main Results:

• Laser pulses induce ultrafast demagnetization and remagnetization processes.
• Analysis of MHD signals reveals significant transient spin texture reorganizations.
• Evidence of a transient surface magnetic texture with reversed curling direction compared to the bulk.

Conclusions:

• Optical methods can prepare metastable complex spin states in magnetic films without external fields.
• Laser-induced surface spin reversals offer new pathways for magnetic data storage and manipulation.
• Understanding transient spin dynamics is key to advancing spintronic device functionalities.