Current-driven vortex wall dynamics is studied by means of a 2-d analytical model and micromagnetic simulation. By constructing a trial function for the vortex wall in the magnetic wire, we analytically solve for domain wall velocity and deformation in the presence of the current-induced spin torque. A critical current for the domain wall transformation from the vortex wall to the transverse wall is calculated. A comparison between the field-and current-driven wall dynamics is carried out. Micromagnetic simulations are performed to verify our analytical results.
We predict a spatially localized magnetic domain wall oscillator upon the application of an external magnetic field and a DC electric current. The amplitude and frequency of the oscillator can be controlled by the field and/or the current. The resulting oscillator could be used as an effective microwave source for information storage application.
The characteristics of magnetic domain-wall depinning driven by a spin transfer torque are dramatically different compared to those driven by a conventional magnetic field. By using the recently derived formalism of the spin torque, we describe key features in the dynamics of geometrically confined domain walls. We numerically calculated the pinning-depinning phase boundary in the presence of the external field and the current.
The switching probability of a single-domain ferromagnet under spin-current
excitation is evaluated using the Fokker-Planck equation(FPE). In the case of
uniaxial anisotropy, the FPE reduces to an ordinary differential equation in
which the lowest eigenvalue $\lambda_1$ determines the slowest switching
events. We have calculated $\lambda_1$ by using both analytical and numerical
methods. It is found that the previous model based on thermally distributed
initial magnetization states \cite{Sun1} can be accurately justified in some
useful limiting conditions.Comment: The 10th Joint MMM/Intermag, HA-0
By using the spin torque model in ferromagnets, we compare the response of
vortex and transverse walls to the electrical current. For a defect-free sample
and a small applied current, the steady state wall mobility is independent of
the wall structure. In the presence of defects, the minimum current required to
overcome the wall pinning potential is much smaller for the vortex wall than
for the transverse wall. During the wall motion, the vortex wall tends to
transform to the transverse wall. We construct a phase diagram for the wall
mobility and the wall transformation driven by the current
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