Enhanced domain wall velocity near a ferromagnetic instability

Assuming a Fermi liquid behavior for $s$-conduction electrons, we rewrite the extended Landau-Lifshitz-Gilbert (LLG) equation renormalized by interactions through the Landau parameters $F^{a}_{l}$ ($l=0,1,2 \cdots$) in an explicit form to describe the dynamic of a domain wall (DW) due to spin transfer torque phenomenon. The interaction between spins of the \textit{s}-conduction electrons explains qualitatively the DW velocity experimental observations in $\mathrm{Ni_{81}}\mathrm{Fe_{19}}$ (Permalloy) recalculated by us without defects or impurity hypothesis. Close to Stoner ferromagnetic instability point where $F^{a}_{0} \approx -0.99$, the DW velocity becomes high ($v^{*}_{DW}\approx 600$ $ms^{-1}$) and critical spin current density becomes reduced ($j^{*}_{c}\approx1\times10^{12}$ $Am^{-2}$) when compared to that calculated by nonadiabatic approach. At the critical point, the DW velocity diverges while critical spin current density at the same point goes to zero. Our theory also provides a prediction to looking for materials in which is possible applies a smallest critical spin current density and observes higher DW velocity.Comment: 7 pages, 5 figure

One-dimensional Gapless Magnons In A Single Anisotropic Ferromagnetic Nanolayer.

Gapless magnons in a plane ferromagnet with normal axis anisotropy are shown to exist besides the usual gapped modes that affect spin dependent transport properties only above a finite temperature. These magnons are one-dimensional objects, in the sense that they are localized inside the domain walls that form in the film. They may play an essential role in the spin dependent scattering processes even down to very low temperatures.9122680

Monitoring the phenolics compounds of the 2G ethanol process.

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Nonequilibrium interacting electrons in a ferromagnet

Dynamics of the magnetization in ferromagnets is examined in the presence of transport electrons allowing the latter to interact. It is found that the existence of inhomogeneities such as domain wall (DW) structures, leads to changes that affect the dynamical structure of the equations of motion for the magnetization. Only in the limit of uniform magnetizations or sufficiently wide DW's, the equations of motion maintain the form they have in the noninteracting case. In this limit, results like the spin torques, the Gilbert parameter, and the DW velocities become renormalized. However the length scale that defines such a limit depends on the strength of the interaction. It is shown that if large ferromagnetic fluctuations exist in the metallic band then the range for which conformity with the noninteracting case holds extends to the limit of arbitrarily narrow DW's.Comment: 4 pages, no figures, revised version, accepted for publication in the PRB's Rapid Communication sectio