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Generation of megahertz-band spin currents using nonlinear spin pumping.
Shingo Watanabe1, Daichi Hirobe1, Yuki Shiomi2
1Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.
Scientific Reports
|July 6, 2017
Summary
Researchers generated megahertz-band voltages using spin pumping and nonlinear magnetization dynamics. This breakthrough overcomes previous limitations in frequency conversion for electronic devices.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spintronics
Background:
- Spin pumping combined with the inverse spin Hall effect generates DC and gigahertz-band (GHz) voltages from microwaves.
- Generating voltages in the megahertz (MHz) band has been challenging due to the GHz-band nature of ferromagnetic resonance.
Purpose of the Study:
- To demonstrate the generation of MHz-band voltages using spin pumping with GHz-band microwaves.
- To explore the underlying mechanism of MHz-band voltage generation via nonlinear magnetization dynamics.
Main Methods:
- Utilizing nonlinear magnetization dynamics in Yttrium Iron Garnet (Y3Fe5O12).
- Applying GHz-band microwaves to induce spin pumping and observe voltage generation.
Main Results:
- Successfully generated MHz-band voltages despite the application of GHz-band microwaves.
- Identified the mechanism as MHz-band oscillation in the amplitude of magnetization precession, rectified by spin pumping.
Conclusions:
- Nonlinear magnetization dynamics enable MHz-band voltage generation via spin pumping.
- This finding offers potential for frequency down-conversion applications due to its simple structure, continuous-wave operation, and tunable output frequency.
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