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Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
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Element-Selective Probing of Ultrafast Ferromagnetic-Antiferromagnetic Order Dynamics in Fe/CoO Bilayers
Chowdhury S Awsaf1, Sangeeta Thakur1, Markus Weißenhofer1,2
1Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, 14195 Berlin, Germany.
Physical Review Letters
|April 11, 2026
Summary
Ultrafast laser pulses demagnetize epitaxial iron/cobalt oxide (Fe/CoO) bilayers. Direct energy transfer from iron to cobalt oxide is the primary demagnetization pathway for 800 nm excitation.
Area of Science:
- Condensed matter physics
- Materials science
- Ultrafast magnetism
Background:
- Epitaxial Fe/CoO bilayers exhibit complex magnetic interactions.
- Understanding ultrafast demagnetization dynamics is crucial for spintronic applications.
Purpose of the Study:
- To investigate the element-resolved ultrafast magnetization dynamics of Fe/CoO bilayers.
- To elucidate the demagnetization mechanisms following optical excitation.
Main Methods:
- Resonant soft-x-ray reflectivity was employed.
- Element-resolved transient magnetic linear dichroism (Co L2 edge) and magnetic circular dichroism (Fe L3 edge) were measured.
- Pump-probe experiments with 120 fs temporal resolution were conducted using 60 fs laser pulses.
Main Results:
- Both antiferromagnetic order in CoO and ferromagnetic order in Fe were lost within 300 fs after excitation.
- Spin-dynamics simulations indicated direct energy transfer from laser-excited electrons in Fe to CoO magnetic moments.
- This energy transfer was identified as the dominant demagnetization channel for 800 nm excitation.
Conclusions:
- The study reveals element-specific ultrafast demagnetization in Fe/CoO bilayers.
- Direct electron-to-magnon energy transfer is a key mechanism for demagnetization in such systems.
- Findings provide insights into controlling magnetism on ultrafast timescales.
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