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Chiral Pumping of Spin Waves.
Tao Yu1, Yaroslav M Blanter1, Gerrit E W Bauer1,2
1Kavli Institute of NanoScience, Delft University of Technology, 2628 CJ Delft, Netherlands.
Physical Review Letters
|January 11, 2020
Summary
We developed a theory for chiral pumping of spin waves into magnetic films using dipolar coupling. This process generates a nonequilibrium magnetization and a chiral spin Seebeck effect via incoherent magnons.
Area of Science:
- Condensed matter physics
- Spintronics
- Magnonics
Background:
- Spin waves are fundamental excitations in magnetic materials.
- Chiral phenomena in magnetism are crucial for novel device applications.
- Controlling spin wave propagation is key for information processing.
Purpose of the Study:
- To theoretically investigate the coherent and incoherent chiral pumping of spin waves.
- To explore the role of dipolar coupling with magnetic transducers in spin wave injection.
- To understand the generation of nonequilibrium magnetization and the chiral spin Seebeck effect.
Main Methods:
- Developing a theoretical framework for spin wave pumping.
- Analyzing the dipolar coupling between a magnetic transducer (nanowire) and a thin magnetic film.
- Investigating the effects of ferromagnetic resonance broadening and temperature gradients.
Main Results:
- Demonstrated coherent and incoherent chiral pumping of spin waves.
- Showcased how nanowire ferromagnetic resonance can inject unidirectional spin waves.
- Established a link between temperature gradients and the chiral spin Seebeck effect via incoherent magnons.
Conclusions:
- The proposed theory provides a mechanism for chiral spin wave injection.
- Dipolar coupling is an effective means to generate spin wave currents.
- The chiral spin Seebeck effect arises from temperature-gradient-driven incoherent magnons.
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