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Updated: May 10, 2025
11:33
All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics
Published on: January 19, 2018
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Femtosecond charge and spin dynamics in a Co50Pt50 alloy
Martin Pavelka1, Simon Marotzke, Ru-Pan Wang2
1Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden.
Structural Dynamics (Melville, N.Y.)
|April 28, 2025
Summary
Advanced X-ray sources like free-electron lasers reveal ultrafast magnetic material dynamics. Femtosecond X-ray pulses show comparable CoPt alloy demagnetization to CoPd, linked to spin-orbit coupling differences.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Ultrafast Spectroscopy
Background:
- Advanced X-ray sources are crucial for studying dynamic processes in magnetic materials.
- X-ray free-electron lasers (XFELs) enable simultaneous observation of femtosecond electron and spin system evolution.
- Transient X-ray absorption spectroscopy and X-ray magnetic circular dichroism resolve spin-split valence state responses to optical excitation.
Purpose of the Study:
- To investigate the femtosecond demagnetization dynamics of laser-excited Cobalt Platinum (CoPt) alloy.
- To utilize circularly polarized ultrashort soft X-ray pulses from the FLASH free-electron laser.
- To probe dynamics at the Cobalt L3-edge absorption.
Main Methods:
- Femtosecond time-resolved X-ray magnetic circular dichroism (XMCD).
- Soft X-ray pulses from a helical afterburner undulator at FLASH.
- Co L3-edge absorption spectroscopy.
Main Results:
- Observed femtosecond demagnetization dynamics in laser-excited CoPt alloy.
- Found comparable demagnetization in Co 3d-states of CoPt despite weaker excitation compared to CoPd.
- Attributed findings to differences in spin-orbit coupling between 3d-4d and 3d-5d elements.
Conclusions:
- Spin-orbit coupling plays a critical role in ultrafast demagnetization dynamics of magnetic alloys.
- CoPt alloys exhibit robust demagnetization behavior influenced by electronic structure and element pairings.
- Femtosecond X-ray techniques provide unprecedented insight into the fundamental mechanisms governing magnetic material responses.
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