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Faster magnetic walls in rough wires
Yoshinobu Nakatani1, André Thiaville, Jacques Miltat
1CNRS-Université Paris-sud, Laboratoire de physique des solides, 91405 Orsay, France.
Nature Materials
|July 5, 2003
Summary
Domain wall (DW) motion in magnetic wires enables data transmission. Surprisingly, edge roughness in low-anisotropy permalloy suppresses the typical velocity breakdown, suggesting roughness engineering for better DW propagation devices.
Area of Science:
- Physics
- Materials Science
- Nanotechnology
Background:
- Information transmission in magnetic devices relies on domain wall (DW) motion along submicrometre magnetic wires.
- High DW velocities (up to 1 km/s) have been observed in moderate fields, notably in low-anisotropy permalloy, which was unexpected given previous findings in high-anisotropy materials.
Purpose of the Study:
- To investigate the behavior of DW propagation in permalloy nanostructures.
- To understand the influence of sample imperfections, specifically edge roughness, on DW velocity.
Main Methods:
- Numerical simulations were employed to model DW propagation dynamics.
- The simulations focused on comparing DW behavior in perfect permalloy strips versus those with rough edges.
Main Results:
- In perfect samples, DW velocity increased with magnetic field up to a threshold, then abruptly decreased, a known phenomenon.
- For samples with rough strip edges, the velocity breakdown was suppressed, indicating a counter-intuitive enhancement of DW propagation stability.
Conclusions:
- Edge roughness in permalloy nanostructures does not hinder, but rather suppresses the velocity breakdown of domain walls.
- Fabrication of nanostructures for DW propagation should consider engineering roughness rather than avoiding it to optimize device performance.