All-optical spin switching under different spin configurations.

Area of Science:

• Femtomagnetism
• All-optical spin switching
• Atomic spin modeling

Background:

• All-optical spin switching is a novel femtomagnetism technique distinct from traditional thermal methods.
• Understanding the fundamental physics of laser-induced spin manipulation is crucial for developing new magnetic technologies.

Purpose of the Study:

• To systematically investigate all-optical spin switching using an atomic spin model, from single spins to large systems.
• To elucidate the role of laser polarization and electron momentum in spin switching dynamics.
• To explore the influence of different magnetic spin structures on the all-optical switching response.

Main Methods:

• Development and application of an atomic spin model for simulating spin dynamics.
• Systematic investigation of spin switching behavior across various system sizes (single spin to over a million spins).
• Analysis of the impact of different laser polarizations (linear, circular) on diverse magnetic spin structures (uniform films, Néel walls, Bloch walls).

Main Results:

• Laser pulses alter the spin-orbit torque relation, enabling spin changes independent of orbital momentum conservation.
• Efficient spin switching requires electron momentum to align with spin orientation, maximizing spin-orbit torque.
• Spin switching efficiency and outcomes are highly dependent on laser polarization and the underlying spin structure, with distinct effects observed on uniform films, Néel walls, and Bloch walls.

Conclusions:

• All-optical spin switching offers a new pathway for ultrafast magnetic control, driven by spin-orbit torques modulated by laser polarization.
• The interaction between laser light and magnetic structures is complex, with polarization dictating the specific spin response.
• These findings provide critical insights into the mechanisms of all-optical spin switching, paving the way for advanced spintronic applications.