Element Specificity of Transient Extreme Ultraviolet Magnetic Dichroism

Area of Science:

• Condensed Matter Physics
• Quantum Mechanics
• Materials Science

Background:

• Transient magnetic circular dichroism (TRMCD) is a powerful technique for probing ultrafast magnetic phenomena.
• Understanding element-specific magnetic dynamics is crucial for developing advanced magnetic materials.

Purpose of the Study:

• To theoretically and experimentally investigate TRMCD in the extreme ultraviolet (EUV) spectral range.
• To validate the extraction of element-specific magnetic moment dynamics from EUV TRMCD signals.
• To compare theoretical predictions with experimental measurements for Co and CoPt.

Main Methods:

• Ab initio real-time time-dependent density functional theory (RT-TDDFT) simulations of magnetization dynamics.
• Calculation of TRMCD using an approximation to the excited-state linear response.
• Experimental measurement of TRMCD spectra for Co and CoPt.

Main Results:

• Demonstrated a method to calculate TRMCD using excited-state linear response approximation.
• Computationally showed that EUV TRMCD can indeed extract element-specific local spin moment dynamics.
• Achieved excellent agreement between theoretical predictions and experimental TRMCD measurements for CoPt, including specific M, N, and O edges.

Conclusions:

• The study confirms the utility of EUV TRMCD for probing element-specific ultrafast magnetism.
• The combination of RT-TDDFT and linear response approximation provides a reliable theoretical framework for TRMCD analysis.
• Excellent agreement with experimental data validates the theoretical approach and the interpretation of TRMCD signals.