Current-induced motion of a domain wall in a magnetic nanowire

The current-induced motion of a magnetic domain wall in a quasi-one-dimensional ferromagnet with both easy-axis and easy-plane anisotropies is studied theoretically. We analyze the spin-transfer-induced torque on a sharp domain wall upon the flow of a dc electric current in the wire. The torque is shown to have two components; one of them acts as a driving force on the domain wall. The other torque component leads to changes to the domain-wall shape in that it forces the magnetic moments to diverge from the easy plane.

Figure 1

Schematic picture of the domain wall.

Figure 2

(Color online) Dependence of the factor $\eta$ on the effective coupling ${\tilde{g}}_0$ for different values of the electron polarization $P$.

Figure 3

(Color online) Coefficient $\zeta$ vs coupling constant ${\tilde{g}}_0$ for different values of $P$.

Figure 4

(Color online) Dependence of the factor $\eta$ on the magnetic splitting $gM$ in the valence band of magnetic semiconductors for different values of the bulk hole density $p$.

Figure 5

(Color online) Coefficient $\zeta$ vs magnetic splitting $gM$ for different values of $p$.

Figure 6

(Color online) Dependence of the parameter $\beta$ on the domain-wall velocity $\tilde{v}$ for different values of the current.