Tatara and Kohno Reply:

Tatara, Gen; Kohno, Hiroshi

doi:10.1103/physrevlett.96.189702

Cited by 350 publications

(755 citation statements)

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“…(3), is perpendicular to the adiabatic spin transfer torque and is referred to as the nonadiabatic spin transfer torque even though some contributions to it occur in the adiabatic limit. Without the nonadiabatic torque, the adiabatic torque in combination with the other terms in the LLG equation leads to intrinsic pinning for currents below a threshold [23]. Intrinsic pinning happens because the wall distorts as it moves and the distortion leads to torques that oppose the motion.…”

Section: Non-local Spin Transfer Torque For a Narrow Domain Wallmentioning

confidence: 99%

“…For narrower domain walls (width < 5 nm), the conduction electron spins traversing the domain wall cannot follow a sharp change in the magnetization and thus contribute to the nonadiabaticity [100,102]; i.e., ballistic spin-mistracking. When the domain wall is extremely narrow (i.e., one or two atomic layers), momentum transfer can occur due to the reflection of electron spins from the domain wall [23]. This class of mechanisms (spin diffusion, spin mistracking, and momentum transfer) generally gives nonlocal spin transfer torques and their contributions depend on the domain wall width.…”

Section: Non-local Spin Transfer Torque For a Narrow Domain Wallmentioning

confidence: 99%

“…The importance of the nonadiabaticity for current-induced domain wall motion, has led to a number of theoretical [23][24][25][98][99][100][101][102][103][104][105][106] and experimental studies [94,[107][108][109][110][111][112] to determine the nonadiabatic spin torque parameter. Several mechanisms for the nonadiabatic spin transfer torque have been proposed.…”

Section: Non-local Spin Transfer Torque For a Narrow Domain Wallmentioning

confidence: 99%

“…On the other hand, when the current flows within a magnetic layer (or nanowire) with a continuously varying magnetization, e.g. domain walls and spin waves, N i ST for onedimensional system is taken as [23][24][25] ) is the spin current velocity corresponding to adiabatic spin transfer torque, P is the spin polarization, j e is the charge current density, M S is the saturation magnetization, and  is the ratio of the nonadiabatic spin transfer torque to the adiabatic one [24,25].…”

Section: Introductionmentioning

confidence: 99%

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Self-consistent calculation of spin transport and magnetization dynamics

et al. 2013

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A spin-polarized current transfers its spin-angular momentum to a local magnetization, exciting various types of current-induced magnetization dynamics. So far, most studies in this field have focused on the direct effect of spin transport on magnetization dynamics, but ignored the feedback from the magnetization dynamics to the spin transport and back to the magnetization dynamics. Although the feedback is usually weak, there are situations when it can play an important role in the dynamics. In such situations, simultaneous, self-consistent calculations of the magnetization dynamics and the spin transport can accurately describe the feedback. This review describes in detail the feedback mechanisms, and presents recent progress in self-consistent calculations of the coupled dynamics. We pay special attention to three representative examples, where the feedback generates non-local effective interactions for the magnetization after the spin accumulation has been integrated out. Possibly the most dramatic feedback example is the dynamic instability in magnetic nanopillars with a single magnetic layer. This instability does not occur without non-local feedback. We demonstrate that full self-consistent calculations generate simulation results in much better agreement with experiments than previous calculations that addressed the feedback effect approximately.The next example is for more typical spin valve nanopillars. Although the effect of feedback is less dramatic because even without feedback the current can make stationary states unstable and induce magnetization oscillation, the feedback can still have important consequences. For instance, we show that the feedback can reduce the linewidth of oscillations, in agreement with experimental observations. A key aspect of this reduction is the suppression of the excitation of short wave length spin waves by the non-local feedback.Finally, we consider nonadiabatic electron transport in narrow domain walls. The non-local feedback in these systems leads to a significant renormalization of the effective nonadiabatic 3 spin transfer torque. These examples show that the self-consistent treatment of spin transport and magnetization dynamics is important for understanding the physics of the coupled dynamics and for providing a bridge between the ongoing research fields of current-induced magnetization dynamics and the newly emerging fields of magnetization-dynamics-induced generation of charge and spin currents.

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Section: Non-local Spin Transfer Torque For a Narrow Domain Wallmentioning

confidence: 99%

Section: Non-local Spin Transfer Torque For a Narrow Domain Wallmentioning

confidence: 99%

Section: Non-local Spin Transfer Torque For a Narrow Domain Wallmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Self-consistent calculation of spin transport and magnetization dynamics

et al. 2013

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“…1,2) Driving a ferromagnetic domain wall by current pulse has also been achieved. Most in-plane magnetic anisotropy systems are in the extrinsic pinning regime, where the wall motion is driven by a non-adiabatic torque, 3,4) while the spin-transfer torque in the intrinsic pinning regime 5) has been reported in perpendicular magnetization material. 6) Recently, several possibilities for using multilayers for fast domain wall motion have been proposed.…”

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confidence: 99%

Efficient stopping of current-driven domain wall using a local Rashba field

Tatara

Saarikoski

Mitsumata

2016

Appl. Phys. Express

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We show theoretically that a locally embedded Rashba interaction acts as a strong pinning center for current-driven domain walls and demonstrate efficient capturing and depinning of the wall using a weak Rashba interaction of the order of 0.01 eV Å. Our discovery is expected to be useful for highly reliable control of domain walls in racetrack memories. © 2016 The Japan Society of Applied Physics F ully electric operated magnetic memories are promising for fast and high-density memories. Switching of the magnetization of a thin ferromagnetic layer by applying an electric current has been accomplished using the spintransfer effect. 1,2) Driving a ferromagnetic domain wall by current pulse has also been achieved. Most in-plane magnetic anisotropy systems are in the extrinsic pinning regime, where the wall motion is driven by a non-adiabatic torque, 3,4) while the spin-transfer torque in the intrinsic pinning regime 5) has been reported in perpendicular magnetization material. 6) Recently, several possibilities for using multilayers for fast domain wall motion have been proposed. 7-10) For ultrahigh density memories, the use of a sequence of domain walls on a patterned wire ("race track") controlled by an electric current, called a racetrack memory, has been proposed. 11) For memory applications of such multi-domain wall devices, techniques to stop a moving wall at an intended position precisely and without delay is essential. An artificial pinning site has been proposed for stopping the wall; 12) however, efficient and reliable stopping is difficult because of the difficulty in fabricating well-controlled and uniform pinning centers. Moreover, fast stopping requires a strong pinning potential, which necessitates a large current density for depinning.In this paper, we propose a highly efficient and reliable mechanism to stop a moving domain wall using a locally embedded Rashba spin-orbit interaction. The Rashba interaction generates a strong effective magnetic field when an electric current is injected. 13,14) This effective field leads to strong pinning of a moving wall at the Rashba region if the applied current density is below the capturing threshold j cap . Moving the wall from the pinning center is performed by applying a high current pulse above the depinning threshold j dep . Rashba pinning is highly reliable because introducing a Rashba interaction by attaching a small thin layer of heavy metals in a controlled manner is easy to implement with the present technology. The present mechanism also has the advantage of lower energy consumption compared with geometrical pinning. The fact that the capturing threshold j cap is lower than j dep indicates that the energy required to shift the wall positions over a distance of multiple pinning sites is much lower than that of the geometrical pinning mechanism.The system we consider to demonstrate the Rashba pinning effect is simple; it includes a ferromagnetic wire with the Rashba interaction locally embedded by attaching a small thin film of heavy metals [ Fig. 1(a)...

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Current Induced Domain‐wall Motion in Magnetic Nanowires

Thomas¹,

Parkin²

2007

Handbook of Magnetism and Advanced Magnetic Materials

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Recent research on current‐induced domain‐wall motion in magnetic nanowires is reviewed. The first part of the article is devoted to theoretical models and micromagnetic simulations. We first describe the magnetic structure of head‐to‐head domain walls, and then discuss theories of their interaction with spin‐polarized current. The role of both adiabatic and nonadiabatic spin‐transfer torques is discussed in the framework of an analytical one‐dimensional model and micromagnetic simulations. The second part of the article reviews recent experimental studies. Both field‐driven and current‐driven excitation and manipulation of domain walls is discussed.

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Tatara and Kohno Reply:

Cited by 350 publications

References 2 publications

Self-consistent calculation of spin transport and magnetization dynamics

Self-consistent calculation of spin transport and magnetization dynamics

Efficient stopping of current-driven domain wall using a local Rashba field

Current Induced Domain‐wall Motion in Magnetic Nanowires

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