Current-driven dynamics of domain walls

in ferromagnetic nanowires

PAPER: G. S. D. Beach, C. Knutson, C. Nistor, M. Tsoi, and J. L. Erskine, “Nonlinear Domain-Wall Velocity Enhancement by Spin-Polarized Electric Current”, Phys. Rev. Lett. 97, 057203 (2006)

ABSTRACT:

The interaction between a dc spin-polarized electric current and a magnetic domain wall in a Permalloy nanowire was studied by high-bandwidth scanning Kerr polarimetry. The full functional dependence of wall velocity on electric current and magnetic field is presented. With the pinning potential nulled by a field, current-induced velocity enhancements exceeded 35 m/s at a current density of ~6´10¹¹ A/m². This large enhancement, more than 10 times that found in pinning-dominated experiments, results in part from an interaction that is nonlinear in current and independent of current direction.

This work was supported by the NSF NIRT program (No. DMR-0404252) and R. A. Welch Foundation (No. F-1015). Instrumentation was developed with support from the NSF IMR program (No. DMR-0216726) and the Texas Coordinating Board (No. ATP-0099). Nanowires were fabricated using facilities of the Center for Nano and Molecular Science and Technology at UT Austin.