The Effect of Polycrystallinity on Skyrmion Logic Devices
ORAL
Abstract
Polycrystallinity commonly occurs in magnetic thin films but the effect of polycrystallinity on magnetization dynamics and its equilibrium is not considered in micromagnetic models. Polycrystals structures mathematically exist as Voronoi tessellation patterns. Each grain possesses distinct magnetic parameters such as saturation magnetization (Ms), uniaxial magnetic anisotropy (Ku1) and preferred magnetization orientations. Here, we investigate the impact of Voronoi-type polycrystallinity in different magnetic material parameters on the equilibrium magnetization. We find that these variations do not hinder the operations of magnetic logic and memory devices with non-trivial geometry and rich interactions.
We chose our skyrmion logic inverter gate (Phys. Rev. B 105, 054411 (2022)) as a device with a myriad of different phenomena of skyrmion-domain wall interactions to be studied under the polycrystalline spatial heterogeneity. We studied the operation stages of the device under the changes of uniaxial anisotropy constant Ku1 and saturation magnetization Ms. Starting from Ku1(initial) = 8×105 J m-3 and Ms(initial) = 5.8×105 A m-1, these parameters were varied in each microcrystalline region with a random gaussian additive noise distribution of ΔX ~ N(0, σ2) (0 mean, σ standard deviation) such that Ku1 = Ku1(initial) + ΔKu1 with σK = 0.1 Ku1(initial), and Ms = Ms(initial) + ΔMs with σK = 0.05 Ms(initial).
Based on the micromagnetic model results, the deviations magnetic material properties due to polycrystallinity do not hinder the operation of the logic devices. We found that this robustness against this type of noise applies not only for skyrmion motion in magnetic tracks but also for more intricate cases of domain wall motion in narrow tracks, selective domain wall pinning, skyrmion gating by domain wall, and magnetic domain extension in non-trivial geometries. These results help better understand the effect of polycrystallinity in magnetic materials and devices.
We chose our skyrmion logic inverter gate (Phys. Rev. B 105, 054411 (2022)) as a device with a myriad of different phenomena of skyrmion-domain wall interactions to be studied under the polycrystalline spatial heterogeneity. We studied the operation stages of the device under the changes of uniaxial anisotropy constant Ku1 and saturation magnetization Ms. Starting from Ku1(initial) = 8×105 J m-3 and Ms(initial) = 5.8×105 A m-1, these parameters were varied in each microcrystalline region with a random gaussian additive noise distribution of ΔX ~ N(0, σ2) (0 mean, σ standard deviation) such that Ku1 = Ku1(initial) + ΔKu1 with σK = 0.1 Ku1(initial), and Ms = Ms(initial) + ΔMs with σK = 0.05 Ms(initial).
Based on the micromagnetic model results, the deviations magnetic material properties due to polycrystallinity do not hinder the operation of the logic devices. We found that this robustness against this type of noise applies not only for skyrmion motion in magnetic tracks but also for more intricate cases of domain wall motion in narrow tracks, selective domain wall pinning, skyrmion gating by domain wall, and magnetic domain extension in non-trivial geometries. These results help better understand the effect of polycrystallinity in magnetic materials and devices.
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Publication: A. M. Cheghabouri, F. Katmis, and M.C. Onbasli, Cascadable direct current driven skyrmion logic inverter gate. Physical Review B, 2022. 105(5): p. 054411.
Presenters
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Mehmet Cengiz Onbasli
Koc University
Authors
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Mehmet Cengiz Onbasli
Koc University
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Arash Mousavi Cheghabouri
Koc University
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Ferhat Katmis
Massachusetts Institute of Technology