Current-Spin Coupling for Ferromagnetic Domain Walls in Fine Wires

Barnes, S. E.; Maekawa, Sadamichi

doi:10.1103/physrevlett.95.107204

Cited by 271 publications

(282 citation statements)

References 18 publications

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“…2. As j increases, R approaches to the asymptotic values expected from equations (8) and (9). On the other hand, it shows rapid increase due to the impurity effect as j is decreased.…”

Section: Discussionmentioning

confidence: 55%

“…However, the Joule heating has been a serious issue because a large current density j is necessary to overcome the pinning, and, therefore, the experiments usually have been done using a short pulse of electric current. The current-velocity relation of the domain-wall motion has been well studied [3][4][5][6][7][8][9] , which is sensitive to the impurity pinning, the Gilbert damping, and nonadiabatic effects.…”

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confidence: 99%

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Universal current-velocity relation of skyrmion motion in chiral magnets

2013

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Current-driven motion of the magnetic domain wall in ferromagnets is attracting intense attention because of potential applications such as racetrack memory. There, the critical current density to drive the motion is B10 9 -10 12 A m À 2 . The skyrmions recently discovered in chiral magnets have much smaller critical current density of B10 5 -10 6 A m À 2 , but the microscopic mechanism is not yet explored. Here we present a numerical simulation of Landau-Lifshitz-Gilbert equation, which reveals a remarkably robust and universal currentvelocity relation of the skyrmion motion driven by the spin-transfer-torque unaffected by either impurities or nonadiabatic effect in sharp contrast to the case of domain wall or spin helix. Simulation results are analysed using a theory based on Thiele's equation, and it is concluded that this behaviour is due to the Magnus force and flexible shape-deformation of individual skyrmions and skyrmion crystal, which enable them to avoid pinning centres.

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“…2. As j increases, R approaches to the asymptotic values expected from equations (8) and (9). On the other hand, it shows rapid increase due to the impurity effect as j is decreased.…”

Section: Discussionmentioning

confidence: 55%

mentioning

confidence: 99%

Universal current-velocity relation of skyrmion motion in chiral magnets

2013

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“…The analogy between the dissipative hydrodynamic equation and the extended LLG equation implies interesting connections between ferromagnetic BECs and conducting ferromagnets. For instance, the current-driven motion of domain walls and spin vortices, which has been investigated in conducting ferromagnets theoretically [17,20,21] and experimentally [22,23], can be investigated also in ferromagnetic BECs by comparison. More interesting phenomena such as the anomalous Hall effect, which is the Hall effect due to the magnetization in a conducting ferromagnet [24][25][26][27], may be investigated in a ferromagnetic BEC from the viewpoint of the interaction between current and spin configuration.…”

Section: Introductionmentioning

confidence: 99%

Dissipative hydrodynamic equation of a ferromagnetic Bose-Einstein condensate: Analogy to magnetization dynamics in conducting ferromagnets

Kudo

Kawaguchi

2011

Phys. Rev. A

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The hydrodynamic equation of a spinor Bose-Einstein condensate (BEC) gives a simple description of spin dynamics in the condensate. We introduce the hydrodynamic equation of a ferromagnetic BEC with dissipation originating from the energy dissipation of the condensate. The dissipative hydrodynamic equation has the same form as an extended Landau-Lifshitz-Gilbert (LLG) equation, which describes the magnetization dynamics of conducting ferromagnets in which localized magnetization interacts with spin-polarized currents. Employing the dissipative hydrodynamic equation, we demonstrate the magnetic domain pattern dynamics of a ferromagnetic BEC in the presence and absence of a current of particles, and discuss the effects of the current on domain pattern formation. We also discuss the characteristic lengths of domain patterns that have domain walls with and without finite magnetization.

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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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Current-Spin Coupling for Ferromagnetic Domain Walls in Fine Wires

Cited by 271 publications

References 18 publications

Universal current-velocity relation of skyrmion motion in chiral magnets

Universal current-velocity relation of skyrmion motion in chiral magnets

Dissipative hydrodynamic equation of a ferromagnetic Bose-Einstein condensate: Analogy to magnetization dynamics in conducting ferromagnets

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

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