Influence of stray fields on the switching-field distribution for bit-patterned media based on pre-patterned substrates

Pfau, Bastian; Günther, C. M.; Guehrs, Erik; Hauet, Thomas; Hennen, T.; Eisebitt, Stefan; Hellwig, Olav

doi:10.1063/1.4896982

Cited by 29 publications

(27 citation statements)

References 25 publications

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“…1(b). The pitch (defined as the distance between the centers of two nanodots) was chosen to be 5 μm to minimize the influence of dipolar effects [25].…”

Section: Experiments Methods and Resultsmentioning

confidence: 99%

Domain-Wall Motion Driven by Laplace Pressure in Co−Fe−B/MgO Nanodots with Perpendicular Anisotropy

Zhang

Vernier

et al. 2018

Phys. Rev. Applied

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We have studied the magnetization reversal of CoFeB-MgO nanodots with perpendicular anisotropy for size ranging from w=400 nm to 1 μm. Contrary to previous experiments, the switching field distribution is shifted toward lower magnetic fields as the size of the elements is reduced with a mean switching field varying as 1/w. We show that this mechanism can be explained by the nucleation of a pinned magnetic domain wall (DW) at the edges of the nanodots where damages are introduced by the patterning process. As the surface tension (Laplace pressure) applied on the DW increases when reducing the size of the nanodots, we demonstrate that the depinning field to reverse the entire elements varies as 1/w. These results suggest that the presence of DWs has to be considered in the switching process of nanoscale elements and open a path toward scalable spintronic devices.

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“…1(b). The pitch (defined as the distance between the centers of two nanodots) was chosen to be 5 μm to minimize the influence of dipolar effects [25].…”

Section: Experiments Methods and Resultsmentioning

confidence: 99%

Domain-Wall Motion Driven by Laplace Pressure in Co−Fe−B/MgO Nanodots with Perpendicular Anisotropy

Zhang

Vernier

et al. 2018

Phys. Rev. Applied

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“…b) Author to whom correspondence should be addressed: eisebitt@mbiberlin.de electrical or magnetic fields and without detrimental effects associated with photoemission-induced charging, and (iii) the technical advantages of operating symmetrically around the optical axis, allowing for high spatial resolution in full-field approaches. Examples for such soft x-ray transmission techniques with spatial resolutions approaching approximately 10 nm are Transmission X-ray Microscopy (TXM), 1,2 Scanning Transmission X-ray Microscopy (STXM), 3 Fourier Transform X-ray Holography (FTH), 4 and Coherent Diffractive Imaging (CDI). 5 As the exit wave of the incident radiation after passage through the sample is detected, all these approaches require suitable soft x-ray transparency of the sample to be investigated.…”

Section: Introductionmentioning

confidence: 99%

A general approach to obtain soft x-ray transparency for thin films grown on bulk substrates

Fohler

Frömmel

Schneider

et al. 2017

Review of Scientific Instruments

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We present a general approach to thin bulk samples to transparency for experiments in the soft x-ray and extreme ultraviolet spectral range. The method relies on mechanical grinding followed by focused-ion-beam milling. It results in a uniformly thin area of high surface quality, suitable for nanoscale imaging in transmission. In a proof-of-principle experiment, nanoscale magnetic bits on a commercial hard drive glass disk are imaged with a spatial resolution below 30 nm by soft x-ray spectro-holography. Furthermore, we demonstrate imaging of a lithographically patterned test object via absorption contrast. Our approach is suitable for both amorphous and crystalline substrates and has been tested for a variety of common epitaxy growth substrates. Lateral thinning areas in excess of 100 μm and a remaining substrate thickness as thin as 150 nm are easily achievable. Our approach allows preserving a previously grown thin film, and from nanofocus electron diffraction, we find no evidence for morphological changes induced by the process, in agreement with numerical simulations of the ion implantation depth distributon. We expect our method to be widely applicable and especially useful for nanoscale imaging of epitaxial thin films.

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“…Primarily, the SFD is determined by two contributions, 1,2 intrinsic variations among the islands and broadening due to dipolar fields from nearby islands. 3,4 The intrinsic distribution of switching field has been particularly attributed to a distribution of intrinsic anisotropy. 5 In turn, the origin of this anisotropy distribution must be related to structural variations among islands.…”

Section: Introductionmentioning

confidence: 99%

“…8 If the island is subjected to considerable dipolar fields from neighboring islands, the SPD will be additionally broadened due to different magnetic configurations of the surrounding islands. 4,8,9 Here, we investigate the SPD in BPM samples with a negligible small dipolar interaction between islands in order to directly compare thermal and intrinsic broadening of the SFD. Using in-field imaging of the islands' magnetic states, we directly show a thermal variation of the switching field at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Thermally induced magnetic switching in bit-patterned media

Pfau

Günther

Hauet

et al. 2017

Journal of Applied Physics

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We have studied the thermal variation of the switching field of magnetic islands at room temperature. A model bit-pattern media composed of an assembly of islands with 80 nm width was fabricated by sputter deposition onto a pre-patterned substrate. Using direct magnetic-contrast imaging of the islands under applied field, we extract the switching probabilities of individual islands. Based on an analytical model for the thermally activated switching of the islands, we are able to determine the intrinsic magnetic anisotropy of each island and, consequentially, a distribution of anisotropies for the island ensemble investigated. In the distribution, we identify a separated group of islands with a particularly small anisotropy. We attribute this group to islands containing misaligned grains triggering the magnetic reversal. At room temperature and slow field sweep rates, the observed thermal broadening of the switching-field distribution is small compared to the intrinsic broadening. However, we illustrate that thermal fluctuations play a crucial role at high sweep rates by extrapolating our results to technological relevant regimes. Published by AIP Publishing.

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Influence of stray fields on the switching-field distribution for bit-patterned media based on pre-patterned substrates

Cited by 29 publications

References 25 publications

Domain-Wall Motion Driven by Laplace Pressure in Co−Fe−B/MgO Nanodots with Perpendicular Anisotropy

Domain-Wall Motion Driven by Laplace Pressure in Co−Fe−B/MgO Nanodots with Perpendicular Anisotropy

A general approach to obtain soft x-ray transparency for thin films grown on bulk substrates

Thermally induced magnetic switching in bit-patterned media

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