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Domain wall creep in magnetic wires.
F Cayssol1, D Ravelosona, C Chappert
1Institut d'Electronique Fondamentale, UMR CNRS 8622, Université Paris Sud, 91405 Orsay, France.
Physical Review Letters
|April 20, 2004
Summary
Domain wall velocity in magnetic wires dramatically slows as wire width decreases, following a 1/4 critical exponent creep process. Edge roughness from patterning causes this behavior, introducing a topological critical field.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Domain walls (DWs) are crucial for magnetic memory technologies.
- Controlling DW dynamics in ultrathin magnetic films is essential for device performance.
- Patterning processes can introduce defects affecting magnetic behavior.
Purpose of the Study:
- Investigate the influence of wire width on 1D domain wall dynamics.
- Determine the mechanism governing domain wall motion in narrow magnetic wires.
- Understand the role of edge roughness in domain wall creep.
Main Methods:
- Fabrication of 2D ultrathin Co films patterned into wires of varying widths (w0).
- Measurement of domain wall velocity (v) as a function of applied magnetic field (H).
- Analysis of velocity-field dependence using creep theory and critical exponents.
Main Results:
- Domain wall velocity significantly decreases with reduced wire width (w0).
- Field dependence follows a creep process with a critical exponent micro=1/4.
- Effective critical field scales inversely with wire width (1/w0).
- Edge roughness introduced by patterning is identified as the primary cause of reduced velocity.
Conclusions:
- Edge roughness in patterned magnetic wires dictates domain wall dynamics.
- A topologically induced critical field, proportional to (1/w0), renormalizes the creep law.
- Understanding these dynamics is key for designing advanced magnetic storage devices.