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Nonlinear domain-wall velocity enhancement by spin-polarized electric current
G S D Beach1, C Knutson, C Nistor
1Department of Physics, The University of Texas at Austin, Austin, TX 78712-0264, USA. gbeach@physics.utexas.edu
Physical Review Letters
|October 10, 2006
Summary
Researchers investigated how electric currents affect magnetic domain walls in Permalloy nanowires. They observed significant velocity enhancements, over 35 m/s, driven by a nonlinear current interaction.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Magnetic domain walls are crucial for magnetic storage technologies.
- Understanding their dynamics under electric current is key to developing advanced spintronic devices.
- Previous studies often focused on current effects under pinning potentials.
Purpose of the Study:
- To investigate the interaction between dc spin-polarized electric current and magnetic domain walls in Permalloy nanowires.
- To determine the full functional dependence of domain wall velocity on electric current and magnetic field.
- To explore current-induced domain wall motion in the absence of pinning potentials.
Main Methods:
- High-bandwidth scanning Kerr polarimetry was employed to probe domain wall dynamics.
- Experiments were conducted on Permalloy nanowires.
- Varying electric current densities and magnetic fields were applied.
Main Results:
- The study presents the complete relationship between domain wall velocity, electric current, and magnetic field.
- Significant current-induced velocity enhancements exceeding 35 m/s were observed at a current density of ~6 x 10^11 A/m^2.
- This enhancement, over 10 times greater than in pinning-dominated regimes, stems from a nonlinear, direction-independent current interaction.
Conclusions:
- A nonlinear current interaction significantly enhances magnetic domain wall velocity in Permalloy nanowires, independent of current direction.
- These findings offer new insights into spin-current interactions and potential for high-speed spintronic devices.
- The observed large velocity enhancements highlight the importance of exploring current effects beyond pinning-dominated scenarios.
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