Depinning probability of a magnetic domain wall in nanowires by spin-polarized currents

Abstract

Current-induced magnetic domain wall motion is attractive for manipulating magnetization direction in spintronics devices, which open a new era of electronics. Up to now, in spite of a crucial significance to applications, investigation on a current-induced domain wall depinning probability, especially in sub-nano to a-few-nanosecond range has been lacking. Here we report on the probability of the depinning in perpendicularly magnetized Co/Ni nanowires in this timescale. A high depinning probability was obtained even for 2-ns pulses with a current density of less than 10 12 A m À 2 . A one-dimensional Landau-Lifshitz-Gilbert calculation taking into account thermal fluctuations reproduces well the experimental results. We also calculate the depinning probability as functions of various parameters and found that parameters other than the coercive field do not affect the transition width of the probability. These findings will allow one to design high-speed and reliable magnetic devices based on the domain wall motion.

Thermal stability of a magnetic domain wall in nanowires

“…Co/Ni multilayers with a perpendicular magnetic easy axis are used throughout this work, in which a well-defined DW motion driven by an adiabatic spin-transfer torque has been observed [12,15,19,20]. The films are deposited by dc-magnetron sputtering onto high-resistivity 3-inch Si wafers.…”

“…To evaluate E/k B T and J C , we first prepare a DW at the Hall cross (initialization) and then apply dc magnetic fields or current pulses, as shown in the schematic illustration in Fig. 1 [15]. The anomalous Hall resistance R H is measured to examine the DW depinning across the Hall cross with a dc current density of less than 5 × 10 10 A/m 2 .…”

“…This is not only a general problem in condensed matter and statistical physics, but it is also an issue of importance for applications to current-induced DW-motion [6] devices, which have been * s-fukami@csis.tohoku.ac.jp proposed and have gathered considerable interest [7][8][9]. The DW depinning induced by electric current [10][11][12][13][14][15] or thermal fluctuation [16][17][18][19][20][21] has been studied, and E for depinning with adiabatic spin-transfer torque generated by the spin-polarized current has been found to be different from that with thermal fluctuation [19,20]. However, physics and the nature of the E/k B T involved in the DW motion and its scaling relation with respect to the device size and thickness have not been elucidated.…”

Effect of spin transfer torque on domain wall motion regimes in [Co/Ni] superlattice wires

“…Thus, the 1D model is insufficient to describe the DW velocities in the stochastic regime. Investigation of current-induced DW motion in the nanosecond timescale [37] might reveal ultra-fast back-and-forth movements of the DW.…”

Magnetization switching schemes for nanoscale three-terminal spintronics devices

“…52) To calculate t W from v DW , the finite width of the DW, the alignment margin, and the depinning time 125) were taken into consideration. Although J th slightly varies with W 71,124) as described later, I C almost linearly decreases with decreasing W [ Fig.…”