Effect of the shape and lateral dimensions on the magnetization reversal in permalloy nanofilms

Ponomareva, A.K.; Uspenskaya, L. S.

doi:10.1016/j.physb.2015.08.034

Cited by 2 publications

(4 citation statements)

References 14 publications

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“…This type of structure is very large compared to the typical dimensions encountered for domain wall-based devices in the literature [18][19][20][21]. The large size is advantageous for the assessment of devices reliability since the domain wall needs to cover a sizeable distance.…”

Section: The Investigated Systemsmentioning

confidence: 99%

“…Furthermore, the AFM profiles reveal a trapezoidal shape instead of a square shape which is a consequence of the etching process being unable to transfer precisely the photolithographically defined structures for all depths. Such variations are caused by shadowing effects during the ion milling and might affect the dynamics of the domain wall propagation as well as the nucleation process [20][21][22]. Material redeposition is seen on the images as side bumps on top of the wire.…”

Section: Characterizationmentioning

confidence: 99%

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Geometrical Dependence of Domain-Wall Propagation and Nucleation Fields in Magnetic-Domain-Wall Sensors

Borie¹,

Kehlberger²,

Wahrhusen³

et al. 2017

Phys. Rev. Applied

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We study the key domain wall properties in segmented nanowires loop-based structures used in domain wall based sensors. The two reasons for device failure, namely the distribution of domain wall propagation field (depinning) and the nucleation field are determined with Magneto-Optical Kerr Effect (MOKE) and Giant Magnetoresistance (GMR) measurements for thousands of elements to obtain significant statistics. Single layers of Ni81Fe19, a complete GMR stack with Co90Fe10/Ni81Fe19 as a free layer and a single layer of Co90Fe10 are deposited and industrially patterned to determine the influence of the shape anisotropy, the magneto-crystalline anisotropy, and the fabrication processes. We show that the propagation field is little influenced by the geometry but significantly by material parameters. Simulations for a realistic wire shape yield a curling mode type of the magnetization configuration close to the nucleation field. Nonetheless, we find that the domain wall nucleation fields can be described by a typical Stoner-Wohlfarth model related to the measured geometrical parameters of the wires and fitted by considering the process parameters. The GMR effect is subsequently measured in a substantial number of devices (3000), in order to accurately gauge the variation between devices. This reveals a corrected upper limit to the nucleation fields of the sensors that can be exploited for fast characterization of working elements.

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Section: The Investigated Systemsmentioning

confidence: 99%

Section: Characterizationmentioning

confidence: 99%

Geometrical Dependence of Domain-Wall Propagation and Nucleation Fields in Magnetic-Domain-Wall Sensors

Borie¹,

Kehlberger²,

Wahrhusen³

et al. 2017

Phys. Rev. Applied

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show abstract

“…Bitter patterns are most commonly examined to investigate magnetic domain or vortex structures of functional materials (e.g., for magnetic applications) at the micrometre scale. [5][6][7][8][9][10] Therefore, micromagnetic information obtained by the Bitter method is usually analysed with respect to the structure of individual (or arrangements of a few) domains in single crystals, or in specifically oriented crystallographic planes.…”

mentioning

confidence: 99%

“…To this end, the Bitter technique is applied to a commercial polycrystalline structural steel (S235JR) sample, which was inhomogeneously deformed by spherical indentation. In contrast to micromagnetic approaches, [5][6][7][8][9][10] the overall magnetic domain distribution is here examined. Thus, macroscopic deviations from a statistical domain distribution caused by deformation gradients and by localised magneto-elastic processes are discussed.…”

mentioning

confidence: 99%

Visualisation of deformation gradients in structural steel by macroscopic magnetic domain distribution imaging (Bitter technique)

Sonntag

Cabeza

Kuntner

et al. 2018

Strain

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While classically used to visualise the magnetic microstructure of functional materials (e.g., for magnetic applications), in this study, the Bitter technique was applied for the first time to visualise macroscopic deformation gradients in a polycrystalline low-carbon steel. Spherical indentation was chosen to produce a multiaxial elastic-plastic deformation state. After removing the residual imprint, the Bitter technique was applied, and macroscopic contrast differences were captured in optical microscopy. To verify this novel characterisation technique, characteristic "hemispherical" deformation zones evolving during indentation were identified using an analytical model from the field of contact mechanics. In addition, near-surface residual stresses were determined experimentally using synchrotron radiation diffraction. It is established that the magnetic domain distribution contrast provides deformation-related information: regions of different domain wall densities correspond to different "hemispherical" deformation zones (i.e., to hydrostatic core, plastic zone and elastic zone, respectively). Moreover, the transitions between these three zones correlate with characteristic features of the residual stress profiles (sign changes in the radial and local extrema in the hoop stress). These results indicate the potential of magnetic domain distribution imaging: visualising macroscopic deformation gradients in fine-grained ferromagnetic material with a significantly improved spatial resolution as compared to integral, mean value-based measurement methods.

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Effect of the shape and lateral dimensions on the magnetization reversal in permalloy nanofilms

Cited by 2 publications

References 14 publications

Geometrical Dependence of Domain-Wall Propagation and Nucleation Fields in Magnetic-Domain-Wall Sensors

Geometrical Dependence of Domain-Wall Propagation and Nucleation Fields in Magnetic-Domain-Wall Sensors

Visualisation of deformation gradients in structural steel by macroscopic magnetic domain distribution imaging (Bitter technique)

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