Current Induced Tilting of Domain Walls in High Velocity Motion along Perpendicularly Magnetized Micron-Sized Co/Ni/Co Racetracks

Ryu, Kwang-Su; Thomas, Luc; Yang, See‐Hun; Parkin, Stuart S. P.

doi:10.1143/apex.5.093006

Cited by 105 publications

(93 citation statements)

References 26 publications

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“…However, the tilt angle in Fig. 3 is opposite to that predicted by micromagnetic models of Pt/Co heterostructures 30,33,39 and observed by MOKE microscopy in Pt/Co/Ni/Co racetracks 43 . More specifically, the angle between the DW normal and the current direction is ≈ −45 • for a left-handed up-down DW (↑←↓) at positive current (see panel IV in Fig.…”

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confidence: 58%

“…A more important difference, however, is that we probe the dynamic structure of the DW during current injection rather than after the current-induced displacement. Starting from a homogeneous magnetization state, we image the fastest DW front sweeping through the sample, which has opposite tilt with respect to the slowest DW front that survives in steady state conditions 43 . Accordingly, we find that the DW front in our measurements is orthogonal to the direction of largest DW velocity recently reported for Pt/Co/AlO x 15 .…”

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confidence: 99%

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Spatially and time-resolved magnetization dynamics driven by spin–orbit torques

et al. 2017

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Current-induced spin-orbit torques (SOTs) represent one of the most effective ways to manipulate the magnetization in spintronic devices. The orthogonal torquemagnetization geometry, the strong damping, and the large domain wall velocities inherent to materials with strong spin-orbit coupling make SOTs especially appealing for fast switching applications in nonvolatile memory and logic units. So far, however, the timescale and evolution of the magnetization during the switching process have remained undetected. Here, we report the direct observation of SOTdriven magnetization dynamics in Pt/Co/AlO x dots during current pulse injection.Time-resolved x-ray images with 25 nm spatial and 100 ps temporal resolution reveal that switching is achieved within the duration of a sub-ns current pulse by the fast nucleation of an inverted domain at the edge of the dot and propagation of a tilted domain wall across the dot. The nucleation point is deterministic and alternates between the four dot quadrants depending on the sign of the magnetization, current, and external field. Our measurements reveal how the magnetic symmetry is broken by the concerted action of both damping-like and field-like SOT and show that reproducible switching events can be obtained for over 10 12 reversal cycles. arXiv:1704.06402v1 [cond-mat.mtrl-sci] 21 Apr 2017Controlling the magnetic state of ultrathin heterostructures using electric currents is key to developing nonvolatile memory devices with minimal static and dynamic power consumption 1 . A promising approach for magnetic switching is based on injecting an in-plane current into a ferromagnet/heavy metal bilayer, where the spin-orbit torques (SOTs) 2,3 resulting from the spin Hall effect and interface charge-spin conversion 4-8 provide an efficient mechanism to reverse the magnetization 1,9,10,12-15 and manipulate domain walls (DWs) [16][17][18][19] .SOT switching schemes can be easily integrated into three-terminal magnetic tunnel junctions having either in-plane 10 or out-of-plane 20 magnetization. Although the threeterminal geometry is more demanding in terms of size, it offers desirable features compared to the two-terminal spin-transfer torque (STT) approach presently used in magnetic random access memories (MRAM) 21 . One such feature is the separation of the read and write current paths in the tunnel junction, which avoids electrical stress of the oxide barrier during writing and allows for independent optimization of the tunneling magnetoresistance during reading. The other crucial feature is the switching speed, which is expected to be extremely fast because the spin accumulation inducing the SOTs is orthogonal to the quiescent magnetization, leading to a negligible incubation delay. Such a delay is a major issue for STT devices, since thermal fluctuations result in a switching time distribution that is several ns wide 22,23 . Furthermore, the SOT-induced magnetization dynamics is governed by strong damping in the monodomain regime 24,25 and fast domain wall motion in the m...

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confidence: 99%

Spatially and time-resolved magnetization dynamics driven by spin–orbit torques

et al. 2017

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“…The current-induced domain wall motion (CIDM) in thin perpendicular magnetized ferromagnetic wires sandwiched between a heavy metal and an oxide has been shown to be very efficient, yielding a high domain wall (DW) velocity at low current density enabling the development of spintronic devices [1][2][3][4][5][6][7][8][9][10][11][12]. In these asymmetric wires, inversion symmetry breaking together with strong spin-orbit interaction (SOI) has two major implications.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of spin Hall effect induced torques for current-driven magnetic domain wall motion: Inner interface effect

Bang

Qiu

et al. 2016

Phys. Rev. B

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We investigate the current-induced domain wall motion in perpendicular magnetized Tb/Co wires with structure inversion asymmetry and different layered structures. We find that the critical current density to drive domain wall motion strongly depends on the layered structure. The lowest critical current density ∼15 MA/cm 2 and the highest slope of domain wall velocity curve are obtained for the wire having thin Co sublayers and more inner Tb/Co interfaces, while the largest critical current density ∼26 MA/cm 2 required to drive domain walls is observed in the Tb-Co alloy magnetic wire. It is found that the Co/Tb interface contributes negligibly to Dzyaloshinskii-Moriya interaction, while the effective spin-orbit torque strongly depends on the number of Tb/Co inner interfaces (n). An enhancement of the antidamping torques by extrinsic spin Hall effect due to Tb rare-earth impurity-induced skew scattering is suggested to explain the high efficiency of current-induced domain wall motion.

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“…The difference in directions of oblique magnetic domain wall movement as a function of the magnetization direction has been reported by some groups, 15,[20][21][22][23] whereas the difference in directions of the BD movement between the wire with the RE dominant magnetization and that with the TM dominant magnetization has not been reported. In order to investigate the BD dynamics in a magnetic wire through the spin injection from the Pt layer, we performed micromagnetic calculations of the BD dynamics in a simple ferromagnetic nanowire with perpendicular magnetic anisotropy based on the Landau-Lifshitz equation with spin-transfer torque term, as follows: 24…”

Section: Resultsmentioning

confidence: 89%

Electric-current-induced dynamics of bubble domains in a ferrimagnetic Tb/Co multilayer wire below and above the magnetic compensation point

et al. 2017

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We investigated the electric-current-induced dynamics of bubble domains in a perpendicularly magnetized ferrimagnetic {Tb/Co}7 multilayer wire with a heavy-metal Pt cap layer. The {Tb/Co}7 wire with the transition-metal-dominant and rare-earth-dominant magnetizations was obtained by changing temperature. We found that the bubble domains moved to the electric current direction with growing in oblique angles when electric current pulses were applied. The oblique directions of the bubble-domain’s growth in the {Tb/Co}7 wire with the transition-metal-dominant and rare-earth-dominant magnetizations were opposite with each other. The micromagnetic simulations imply that these oblique growths are accounted by the spin injection from the Pt layer via the spin Hall effect.

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Current Induced Tilting of Domain Walls in High Velocity Motion along Perpendicularly Magnetized Micron-Sized Co/Ni/Co Racetracks

Cited by 105 publications

References 26 publications

Spatially and time-resolved magnetization dynamics driven by spin–orbit torques

Spatially and time-resolved magnetization dynamics driven by spin–orbit torques

Enhancement of spin Hall effect induced torques for current-driven magnetic domain wall motion: Inner interface effect

Electric-current-induced dynamics of bubble domains in a ferrimagnetic Tb/Co multilayer wire below and above the magnetic compensation point

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