Dynamics of domain wall depinning driven by a combination of direct and pulsed currents

The current-induced depinning of a domain wall from an artificial pinning site is investigated in Permalloy nanowires. The depinning probability exhibits an oscillatory dependence on the current pulse length, which is, surprisingly, reduced when a dc current of the same polarity is added to the current pulse. By contrast, the depinning probability increases when dc and pulsed currents have opposite polarities even though the total current flowing though the device is smaller. These results are understood within an analytical one-dimensional model of the domain wall dynamics. (C) 2008 American Institute of Physics.