Comparing ultrafast demagnetization rates between competing models for finite temperature magnetism

Area of Science:

• Condensed matter physics
• Ultrafast magnetization dynamics

Background:

• Finite temperature magnetism is crucial for understanding magnetic materials.
• Current models, like rigid band and localized spins, offer competing descriptions.
• Ultrafast demagnetization is a key phenomenon in spintronics.

Purpose of the Study:

• To resolve the controversy in ultrafast magnetization dynamics.
• To compare the predictive power of rigid band versus localized spin models.
• To determine the suitability of these models for describing experimental results.

Main Methods:

• Investigated ultrafast demagnetization rates.
• Employed a rigid band structure Stoner-like approach.
• Utilized a system of localized spins model.
• Compared theoretical calculations with experimental data.

Main Results:

• Localized spin system calculations yielded demagnetization rates comparable to experimental values.
• Rigid band approach calculations showed negligible demagnetization.
• The discrepancy persisted even with instantaneous microscopic spin-flip processes.

Conclusions:

• Localized spin models provide accurate predictions for ultrafast demagnetization.
• Rigid band structure calculations are inadequate for quantitative agreement with experiments.
• The choice of model is critical for understanding finite temperature magnetism dynamics.