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Element-specific visualization of dynamic magnetic coupling in a Co/Py bilayer microstructure
Thomas Feggeler1,2, Ralf Meckenstock3, Detlef Spoddig3
1Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47048, Duisburg, Germany. tfeggeler@lbl.gov.
Scientific Reports
|November 5, 2022
Summary
We visualized magnetic excitations in Permalloy (Py) and Cobalt (Co) bilayers using scanning transmission X-ray microscopy. Angular momentum transfer between Py and Co was observed, revealing insights into magnetic exchange interactions.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Ferromagnetic resonance (FMR) is crucial for understanding magnetic dynamics.
- Characterizing coupled magnetic systems requires element-specific analysis.
- Previous studies lacked time-resolved, spatially resolved visualization of coupled magnetic excitations.
Purpose of the Study:
- To visualize element-specific, time-resolved ferromagnetic resonance (FMR) excitations in a Permalloy (Py) disk-Cobalt (Co) stripe bilayer.
- To investigate the dynamics of magnetization precession and angular momentum transfer between Py and Co.
- To elucidate the origin of an unexpected third resonance observed in the bilayer system.
Main Methods:
- Utilized a combination of ferromagnetic resonance (FMR) and scanning transmission X-ray microscopy (STXM-FMR).
- Achieved picosecond (ps) time resolution and nanometer spatial resolution.
- Recorded snapshots of local magnetization precession for individual elements (Py and Co).
Main Results:
- Demonstrated element-specific imaging of magnetization precession dynamics.
- Observed bidirectional angular momentum transfer between the Py disk and Co stripe at their respective resonances.
- Identified an unexpected third resonance in the integral FMR spectrum and STXM-FMR experiments.
Conclusions:
- The study provides unprecedented visualization of coupled magnetic dynamics in a Py/Co bilayer.
- Magnetic exchange coupling between Py and Co is identified as the governing mechanism for the third resonance.
- Stray field influence on the Co stripe results in a phase difference in magnetization precession.
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