Observation of the intrinsic pinning of a magnetic domain wall in a ferromagnetic nanowire

Koyama, Tanetoshi; Chiba, Daichi; Ueda, Kunihiro; Kondou, Kouta; Tanigawa, H.; Fukami, Shunsuke; Suzuki, T.; Ohshima, Norikazu; Ishiwata, N.; Nakatani, Yoshinobu; Kobayashi, Kensuke; Ono, Teruo

doi:10.1038/nmat2961

Cited by 324 publications

(319 citation statements)

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“…32,33 Although to our knowledge no experiments have been reported in which the DWs take a Bloch type or a Neel type at ν = 2/3, the DW switching between the two types might be triggered in the confinement similar to in a ferromagnetic nanowire. 45 In these contexts, our experiments provide NMR evidence that a fragile state of DWs can survive in the confinement, which offers a key result to advance the QH ferromagnetism from a bulk regime to a nanoscale regime. However, it is well-known that nanoscale NMR experiments based on optical detection have been intensively conducted using nitrogen-vacancy (NV) centers in diamond.…”

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confidence: 77%

Localized NMR Mediated by Electrical-Field-Induced Domain Wall Oscillation in Quantum-Hall-Ferromagnet Nanowire

et al. 2016

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We present fractional quantum Hall domain walls confined in a gate-defined wire structure. Our experiments utilize spatial oscillation of domain walls driven by radio frequency electric fields to cause nuclear magnetic resonance. The resulting spectra are discussed in terms of both large quadrupole fields created around the wire and hyperfine fields associated with the oscillating domain walls. This provides the experimental fact that the domain walls survive near the confined geometry despite of potential deformation, by which a localized magnetic resonance is allowed in electrical means.

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confidence: 77%

Localized NMR Mediated by Electrical-Field-Induced Domain Wall Oscillation in Quantum-Hall-Ferromagnet Nanowire

et al. 2016

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“…5) is of the order of 10 11 A=m 2 , which is consistent with experimental results. 6) In this case, v c is approximately 2 m=s, and the capturing time is τ cap = 250 ns if α = 0.01 and if~| v c~R ( 1. Since this seems rather slow, systems having either larger K ⊥ or a larger Gilbert damping parameter α are favorable for fast devices.…”

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confidence: 93%

“…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][8][9][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.…”

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confidence: 99%

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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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“…Recently, magnetic nanowires have been the subject of numerous studies because of their unique physical properties and promising applications in spin-related nanotechnologies such as high-density magnetic recording, magnetic field sensors, magnetic nanoprobes for spin-polarized microscopy and cell manipulation in biomedical technology [5][6][7][8][9]. In particular, ferromagnetic nanowires are ideal one-dimensional nanostructures for studying the motion, manipulation and logic operation of magnetic domain walls [10][11][12] as well as the predicted ballistic anisotropic magnetoresistance [13].…”

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confidence: 99%