Observation of thermally activated domain wall transformations

Laufenberg, M.; Backes, Dirk; Bührer, W.; Bedau, D.; Kläui, Mathias; Rüdiger, Ulrich; Vaz, C. A. F.; Bland, J. A. C.; Heyderman, Laura J.; Nolting, F.; Cherifi, S.; Locatelli, Andrea; Belkhou, Rachid; Heun, S.; Bauer, E.

doi:10.1063/1.2168677

Cited by 106 publications

(116 citation statements)

References 23 publications

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“…3,19 However, although both DW types are energy minima, there is not enough thermal activation at room temperature for the TDW which is initially created to overcome the energy barrier which separates it from the vortex wall configuration. 20 The perpendicular arm is either placed outside the curvature of the C, forming a T structure ͑"out" type on the top left diagram of Fig. 2͒, or inside, forming an upside down T structure ͑"in" type on the bottom left diagram of Fig.…”

Section: Methodsmentioning

confidence: 99%

Mechanism for domain wall pinning and potential landscape modification by artificially patterned traps in ferromagnetic nanowires

et al. 2009

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The interaction mechanism between transverse domain walls ͑TDWs͒ in Permalloy nanowires and artificially patterned traps is studied using high-sensitivity spatially resolved magneto-optical Kerr effect measurements and numerical simulations. T-shaped trap geometries are considered, where a DW traveling in the horizontal arm is pinned by the vertical arm. Pinning strengths as well as potential energy modifications created by the traps are measured, and the roles of the different DW characteristic parameters, such as the DW core orientation and the magnetic charge distribution within the DW, are presented. It is found that whether or not the core of the DW is aligned with the transverse arm of the T structure affects the shape of the main potential experienced by the DW, whereas the pinning strength strongly depends on which side of the V-shaped TDW interacts with the trap. The role of the magnetostatic interaction between the charge of the DW and the charge present at the junction is discussed.

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Section: Methodsmentioning

confidence: 99%

Mechanism for domain wall pinning and potential landscape modification by artificially patterned traps in ferromagnetic nanowires

et al. 2009

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“…In comparison to other systems, the stability of the vortex domain wall is pushed to narrower and thinner structures than for either Py [17] or Co [18], which can now be directly understood as arising from the materials properties dependence of Equation 3…”

Section: Resultsmentioning

confidence: 99%

“…The energetically favoured state is determined by the interplay between dipolar and exchange energy contributions which scale differently with the geometry. Beyond such qualitative considerations, for the workhorse system Permalloy, the quantitative details of the phase diagram are well known [13,17], however, the materials parameters of the system also influence the range of sizes where the different domain wall types are stable as has been shown for the case of cobalt [18].…”

Section: Introductionmentioning

confidence: 99%

“…For the imaging of the domain wall spin configurations in rings of other materials, previous work has employed electron holography [21] or Lorentz microscopy, which require that the samples are fabricated on delicate membranes for the transmission measurements [10], photo-emission electron microscopy [17,18,31], which is mainly available at large-scale facilities and can be limited in its resolution, or magnetic force microscopy (MFM) [9,[32][33][34], which can modify the spin configuration of the sample and is however sensitive only to the stray magnetic field from a sample and therefore harder to relate directly to the spin structures obtained from simulations. Therefore, in this paper we chose the imaging technique SEMPA [26], which is a powerful lab-based method with an excellent spatial resolution of less than 20 nm and which can provide quantitative direct information concerning the spin configurations [35].…”

Section: Experimental and Numericsmentioning

confidence: 99%

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Domain wall spin structures in mesoscopic Fe rings probed by high resolution SEMPA

Krautscheid¹,

Reeve²,

Lauf³

et al. 2016

J. Phys. D: Appl. Phys.

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We present a combined theoretical and experimental study of the energetic stability and accessibility of different domain wall spin configurations in mesoscopic magnetic iron rings. The evolution is investigated as a function of the width and thickness in a regime of relevance to devices, while Fe is chosen as a material due to its simple growth in combination with attractive magnetic properties including high saturation magnetization and low intrinsic anisotropy. Micromagnetic simulations are performed to predict the lowest energy states of the domain walls, which can be either the transverse or vortex wall spin structure, in good agreement with analytical models, with further simulations revealing the expected low temperature configurations observable on relaxation of the magnetic structure from saturation in an external field. In the latter case, following the domain wall nucleation process, transverse domain walls are found at larger widths and thicknesses than would be expected by just comparing the competing energy terms demonstrating the importance of metastability of the states. The simulations are compared to high spatial resolution experimental images of the magnetization using scanning electron microscopy with polarization analysis to provide a phase diagram of the various spin configurations. In addition to the vortex and simple symmetric transverse domain wall, a significant range of geometries are found to exhibit highly asymmetric transverse domain walls with properties distinct from the symmetric transverse wall.Simulations of the asymmetric walls reveal an evolution of the domain wall tilting angle with ring thickness which can be understood from the thickness dependencies of the contributing energy terms. Analysis of all the data reveals that in addition to the geometry, the influence of materials properties, defects and thermal activation all need to be taken into account in order to understand and reliably control the experimentally accessible states, as needed for devices.2

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“…In thin film wires, the two domain wall types that occur are transverse and vortex walls and the latter contains a vortex core. 12 To properly explore this magnetic behavior, in particular the transformations to and from the vortex walls, an imaging technique is required that provides an accurate determination of the vortex's spin structure and polarity. Off-axis electron holography is a powerful method for studying the in-plane component of magnetic structures.…”

mentioning

confidence: 99%

Quantitative determination of vortex core dimensions in head-to-head domain walls using off-axis electron holography

Junginger

Kläui

Backes

et al. 2008

Applied Physics Letters

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In this paper, we present a complete three-dimensional characterization of vortex core spin structures, which is important for future magnetic data storage based on vortex cores in disks and in wires. Using electron holography to examine vortices in patterned Permalloy devices we have quantitatively measured the in-plane and out-of-plane magnetization of a vortex core. Observed core widths and integrated phase shifts agree well with those derived from micromagnetic simulations.

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Observation of thermally activated domain wall transformations

Cited by 106 publications

References 23 publications

Mechanism for domain wall pinning and potential landscape modification by artificially patterned traps in ferromagnetic nanowires

Mechanism for domain wall pinning and potential landscape modification by artificially patterned traps in ferromagnetic nanowires

Domain wall spin structures in mesoscopic Fe rings probed by high resolution SEMPA

Quantitative determination of vortex core dimensions in head-to-head domain walls using off-axis electron holography

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