Domain wall pinning in ultra-narrow electromigrated break junctions

Reeve, Robert M.; Loescher, André; Mawass, Mohamad‐Assaad; Hoffmann‐Vogel, Regina; Kläui, Mathias

doi:10.1088/0953-8984/26/47/474207

Cited by 6 publications

(8 citation statements)

References 69 publications

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“…In order to avoid magnetostrictive contributions we choose Py as our magnetic material and use a notched half-ring geometry where we can control the presence and position of DWs in the structure at remanence, as depicted in Figure 1. The system and process of nanocontact fabrication are described in detail in [58]. In the initial state, the contact is around 70 nm wide at the notch position.…”

Section: A Experimentsmentioning

confidence: 99%

“…In this work we employ our previously established approach of tailoring the size of magnetic nanocontacts in clean UHV conditions [22,49,58] to study the evolution of intrinsic DWMR for nanocontacts in a regime where the contacts are expected to be a few nm in size.…”

Section: Introductionmentioning

confidence: 99%

“…The electromigration procedure is subsequently performed in order to narrow down the sample at the region of highest current density, which corresponds to the notch, as detected by the concurrent increase in resistance of the sample from the initial state of around 436 Ω. The magnetotransport characterization is then carried out for the new contact state and the whole process is iterated until the contact size has been reduced to the expected sub-nm regime [58].…”

Section: Introductionmentioning

confidence: 99%

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Scaling of intrinsic domain wall magnetoresistance with confinement in electromigrated nanocontacts

et al. 2019

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In this work we study the evolution of intrinsic domain wall magnetoresistance (DWMR) with domain wall confinement. Clean permalloy notched half-ring nanocontacts are fabricated using a special ultra-high vacuum electromigration procedure to tailor the size of the wire in-situ and through the resulting domain wall confinement we tailor the domain wall width from a few tens of nm down to a few nm. Through measurements of the dependence of the resistance with respect to the applied field direction we extract the contribution of a single domain wall to the MR of the device, as a function of the domain wall width in the confining potential at the notch. In this size range, an intrinsic positive MR is found, which dominates over anisotropic MR, as confirmed by comparison to micromagnetic simulations. Moreover, the MR is found to scale monotonically with the size of the domain wall, δ DW , as 1/δ b DW , with b = 2.31 ± 0.39. The experimental result is supported by quantum-mechanical transport simulations based on ab-initio density functional theory calculations.arXiv:1812.05689v1 [cond-mat.mes-hall]

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Section: A Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Scaling of intrinsic domain wall magnetoresistance with confinement in electromigrated nanocontacts

et al. 2019

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“…15 Great progress has been made in the fabrication of nano-contacts, which can be manufactured down to ∼ 1 nm width. 16 Notches in ferromagnetic films can be used to trap a domain wall (DW), where the length and width can be manipulated. DW movement has been observed in these constructions 17 and their resistivity has been investigated.…”

Section: Introductionmentioning

confidence: 99%

Local spin transfer torque and magnetoresistance in domain walls with variable width

Kazemi,

Eggert,

Sedlmayr

2020

Preprint

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Use of a spin polarized current for the manipulation of magnetic domain walls in ferromagnetic nanowires has been the subject of intensive research for many years. Recently, due to technological advancements, creating nano-contacts with special characteristics is becoming more and more prevalent. We now present a full quantum investigation of the magnetoresistance and the spin transfer torque in a domain wall, which is embedded in a nano-contact of Ni80Fe20, where the size of the domain wall becomes a relevant tunable parameter. The dependence on the domain wall width as well as the spatial dependence of the torque along the domain wall can be analyzed in complete detail. The magnetoresistance drops with increasing domain wall width as expected, but also shows characteristic modulations and points of resonant spin-flip transmission. The spin transfer torque has both significant in-plane and out-of-plane contributions even without considering relaxation. A closer inspection identifies contributions from the misalignment of the spin density for short domain walls as well as an effective gauge field for longer domain walls, both of which oscillate along the domain wall.

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“…Magnetic multilayers with out-of-plane magnetization are essential ingredients in spintronic applications, in particular, they turn out to be suitable in spin-transfer torque devices like magnetic random access memory (MRAM) [28][29][30][31]. They have also been employed in domain wall structures with narrow domain walls which are currently a subject of great interest [32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Gilbert damping in binary magnetic multilayers

Barati

Cinal

2017

Phys. Rev. B

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We present quantum mechanical calculations of the Gilbert damping constant α in ultrathin L1 0 [Co/NM] N superlattices and (001) fcc [Co/NM] N magnetic multilayers built of cobalt and nonmagnetic metals NM = Cu, Ag, Pd, Pt, and Au. The calculations are performed within a realistic nine-orbital tight-binding model of the band structure including spin-orbit interaction. The dependence of α on the stacking number N , ferromagnetic and nonmagnetic layer thicknesses as well as the electron scattering rate is investigated. The damping constant is shown to be the sum of a constant term (bulklike) and a 1/N term (due to external surfaces) which arise from interand intraband electronic transitions, respectively. The calculated α is found to be enhanced in the considered multilayers in comparison with its values for bulk Co and their bilayer counterparts with the same total Co thickness. The origin of this enhancement and the variation of α with the geometric structure of the multilayers are further investigated by analyzing the damping contributions from individual atomic layers. The obtained theoretical results for the damping constant are shown to be in good agreement with previous experimental observations in magnetic multilayers. In particular, the experimentally observed linear dependence on the ratio of NM (Pd or Pt) and Co layer thicknesses is reproduced in the present calculations.

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Domain wall pinning in ultra-narrow electromigrated break junctions

Cited by 6 publications

References 69 publications

Scaling of intrinsic domain wall magnetoresistance with confinement in electromigrated nanocontacts

Scaling of intrinsic domain wall magnetoresistance with confinement in electromigrated nanocontacts

Local spin transfer torque and magnetoresistance in domain walls with variable width

Gilbert damping in binary magnetic multilayers

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