Real-Space Observation of Current-Driven Domain Wall Motion in Submicron Magnetic Wires

Yamaguchi, Akinobu; Ono, Teruo; Nasu, Saburo; Miyake, Koji; Mibu, Ko; Shinjo, Teruya

doi:10.1103/physrevlett.92.077205

Cited by 935 publications

(415 citation statements)

References 23 publications

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“…Depending on the driving force, conventionally magnetic field and, more recently, spin-polarized current [4][5][6][7][8][9][10][11][12][13] , the propagation of DWs changes from a simple translation to more complex precessional modes 14 . Experimentally, indirect evidence of this transition is found from a sudden drop in the wall's velocity [15][16][17][18] , but direct observation of the precessional modes is lacking.…”

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confidence: 99%

Direct observation of the coherent precession of magnetic domain walls propagating along permalloy nanowires

et al. 2006

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The dynamics of the motion of domain walls (DWs) in magnetic materials has been extensively explored theoretically 1-3 . Depending on the driving force, conventionally magnetic field and, more recently, spin-polarized current 4-13 , the propagation of DWs changes from a simple translation to more complex precessional modes 14 . Experimentally, indirect evidence of this transition is found from a sudden drop in the wall's velocity [15][16][17][18] , but direct observation of the precessional modes is lacking. Here we show experimentally, using a combination of quasi-static and real-time measurement techniques, that DWs propagate along permalloy nanowires with a periodic variation in the chirality of the walls. The frequency of this oscillation is consistent with a precession of the propagating DW, increasing linearly with field according to the Larmor precession frequency. Current in the nanowire, large enough to significantly influence the DW velocity 18,19 , has little effect on the precession frequency but can be used to adjust the phase of the wall's precession. The highly coherent and reproducible motion of the DW revealed by our studies demonstrates that the DW is a well-defined macroscopic object whose phase is inextricably interlinked to the distance travelled by the DW.With the advent of magnetic nanowires of dimensions comparable to magnetic DW widths, it is possible to imagine that DWs propagating along such wires will exhibit a well-defined precessional mode due to confinement. In contrast, in extended structures, which have been extensively studied in the past, many modes are accessible 1,20 . Permalloy nanowires are attractive because they exhibit large anisotropic magnetoresistance (AMR) so that transverse and vortex walls can be readily detected and identified by resistance measurements. Furthermore, by breaking the onedimensional symmetry of the nanowire with a notch along one of its edges, the chirality of the DW can also be discerned 21 . Here, notched nanowires are used to directly show that the chirality of transverse DWs periodically reverses as the walls propagate in the precessional regime. This precessional motion is also detected in real time using time-resolved resistance measurements, which show that the precessional motion is, surprisingly, highly coherent.A scanning electron microscopy image of a typical permalloy nanowire with two contact lines, labelled A and B, is shown in Fig. 1a. Using a suitable field sequence (see the Methods section), a DW is introduced into section A-B of the nanowire by injecting a voltage pulse into contact line A. A magnetic field, H, is applied along the wire during the voltage pulse injection to assist the subsequent propagation of a DW. A fraction of the injected voltage pulse flows into section A-B, thereby injecting current into the nanowire as the DW propagates along it. The current density that flows into the nanowire scales as ∼0.5 × 10 8 A cm −2 V −1 . Positive current is defined as current flowing from line A to B.The existence of a DW in sectio...

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Direct observation of the coherent precession of magnetic domain walls propagating along permalloy nanowires

et al. 2006

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“…There are mainly two ways to utilize the STT: one is current-induced magnetization switching (CIMS) in magnetic nanopillars 2,[7][8][9][10][11][12] , and the other is current-induced domain wall motion (CIDWM) in magnetic nanowires 1,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] . In particular, the latter is promising for applications in which a domain wall (DW) moves numerous times within several nanoseconds' duration 4 , or in which numerous DWs are shifted simultaneously 6 .…”

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

et al. 2013

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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.

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“…Current-induced DW motion is of particular interest because it enables the position of DW to be controlled electrically without applying an external magnetic field [1][2][3][4][7][8][9][10][11][12][13][14][16][17][18][19][20][21] . The electric field effect on magnetic materials has been actively studied recently, because magnetic properties can be controlled electrically [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] , when a field-effect-device structurethat is, one consisting of a top-gate electrode, a dielectric insulator layer (or a liquid electrolyte), and a ferromagnetic layer-is used to modulate a carrier density.…”

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Electric-field control of magnetic domain-wall velocity in ultrathin cobalt with perpendicular magnetization

et al. 2012

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Controlling the displacement of a magnetic domain wall is potentially useful for information processing in magnetic non-volatile memories and logic devices. A magnetic domain wall can be moved by applying an external magnetic field and/or electric current, and its velocity depends on their magnitudes. Here we show that the applying an electric field can change the velocity of a magnetic domain wall significantly. A field-effect device, consisting of a topgate electrode, a dielectric insulator layer, and a wire-shaped ferromagnetic Co/Pt thin layer with perpendicular anisotropy, was used to observe it in a finite magnetic field. We found that the application of the electric fields in the range of ± 2-3 mV cm − 1 can change the magnetic domain wall velocity in its creep regime (10 6 -10 3 m s − 1 ) by more than an order of magnitude. This significant change is due to electrical modulation of the energy barrier for the magnetic domain wall motion.

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Real-Space Observation of Current-Driven Domain Wall Motion in Submicron Magnetic Wires

Cited by 935 publications

References 23 publications

Direct observation of the coherent precession of magnetic domain walls propagating along permalloy nanowires

Direct observation of the coherent precession of magnetic domain walls propagating along permalloy nanowires

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

Electric-field control of magnetic domain-wall velocity in ultrathin cobalt with perpendicular magnetization

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