Figure 3: Domain wall velocity as a function of applied magnetic field for different values of x.
From: Stable ultrahigh-density magneto-optical recordings using introduced linear defects
Far away (-578 µm) from the line-defect ‘ridge’ at x = 0, the velocity takes off rapidly with field near Hcrit. Well below Hcrit, the nonlinear v–H curves follow13 v(H) ∝ exp[-Up/kBT)(Hcrit/H)μ], where Up is the collective pinning energy scale, kB is the Boltzmann constant, T is temperature, and μ = 1/4 is the glassy dynamical exponent related to the roughness exponent; see ref. 14. Hcrit grows on the approach to the line defect (see Fig. 4a). Inset, a square Kerr rotation (magnetization) hysteresis characteristic of perpendicular anisotropy of our film in Fig. 2a.
