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Femtosecond Laser Pulse Driven Caustic Spin Wave Beams.
S Muralidhar1, R Khymyn1, A A Awad1
1Physics Department, University of Gothenburg, 412 96 Gothenburg, Sweden.
Physical Review Letters
|February 5, 2021
Summary
Researchers controlled spin wave direction using light and magnetic fields. This demonstrates a method for designing magnonic devices with tunable spin wave propagation patterns.
Area of Science:
- Condensed matter physics
- Quantum information science
- Nanotechnology
Background:
- Controlling spin wave directionality is crucial for developing wave-based computing, particularly in magnonics.
- All-optical methods offer precise control over spin wave generation and manipulation.
Purpose of the Study:
- To demonstrate control over spin wave directionality using an all-optical source.
- To investigate the influence of magnetic fields on spin wave propagation patterns.
Main Methods:
- Utilized an all-optical pointlike source based on frequency comb rapid demagnetization to generate continuous spin waves.
- Applied a detuning magnetic field relative to the ferromagnetic resonance (FMR) to alter spin wave propagation.
Main Results:
- Observed X-shaped caustic spin wave patterns at 70° propagation angles, consistent with theoretical predictions.
- Demonstrated a transition from caustic patterns to uniaxial spin wave propagation by tuning the light source harmonic near FMR.
- Showcased field-controlled propagation patterns and directionality of optically emitted short-wavelength spin waves.
Conclusions:
- Optically generated spin waves exhibit controllable directionality through magnetic field manipulation.
- The observed phenomena provide new degrees of freedom for designing advanced magnonic devices.
- This work advances the fundamental understanding and practical application of spin waves in computing.
