Micromagnetic study of spin-transfer-torque switching of a ferromagnetic cross towards multi-state spin-transfer-torque based random access memory

Roy, Uma; Pramanik, Tanmoy; Tsoi, Maxim; Register, Leonard F.; Banerjee, S.

doi:10.1063/1.4811230

Cited by 13 publications

(12 citation statements)

References 22 publications

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“…This magnetization configuration is similar to the ground state of the nano-scale cross. 49 Such magnetization alignment should result in the BVMSW modes propagating along the cross arms, which were measured in spin wave transmission experiments. At higher magnetic fields, the cross magnetization saturates along the field direction.…”

Section: Resultsmentioning

confidence: 99%

Spin wave scattering and interference in ferromagnetic cross

Nanayakkara

Jacob

Kozhanov

2015

Journal of Applied Physics

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Magnetostatic spin wave scattering and interference across a CoTaZr ferromagnetic spin wave waveguide cross junction were investigated experimentally and by micromagnetic simulations. It is observed that the phase of the scattered waves is dependent on the wavelength, geometry of the junction, and scattering direction. It is found that destructive and constructive interference of the spin waves generates switching characteristics modulated by the input phase of the spin waves. Micromagnetic simulations are used to analyze experimental data and simulate the spin wave scattering and interference. V

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Section: Resultsmentioning

confidence: 99%

Spin wave scattering and interference in ferromagnetic cross

Nanayakkara

Jacob

Kozhanov

2015

Journal of Applied Physics

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“…New applications in varied fields such as energy storage 1 , nanoscale photonics 2 , plasmonic nanostructures 3 , multi-bit magnetic memory 4 , terabit per square inch magnetic recording 5 , and bio-nanoparticles 6, 7 require high-throughput patterning with complex shape control at the nanoscale. Shaped nanopatterns exhibit novel optical, mechanical, and morphological properties that are exploited in various ways by these emerging fields.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics modeling framework for overcoming nanoshape retention limits of imprint lithography

Cherala¹,

Sreenivasan²

2018

Microsyst Nanoeng

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Complex nanoshaped structures (nanoshape structures here are defined as shapes enabled by sharp corners with radius of curvature <5 nm) have been shown to enable emerging nanoscale applications in energy, electronics, optics, and medicine. This nanoshaped fabrication at high throughput is well beyond the capabilities of advanced optical lithography. While the highest-resolution e-beam processes (Gaussian beam tools with non-chemically amplified resists) can achieve <5 nm resolution, this is only available at very low throughputs. Large-area e-beam processes, needed for photomasks and imprint templates, are limited to ~18 nm half-pitch lines and spaces and ~20 nm half-pitch hole patterns. Using nanoimprint lithography, we have previously demonstrated the ability to fabricate precise diamond-like nanoshapes with ~3 nm radius corners over large areas. An exemplary shaped silicon nanowire ultracapacitor device was fabricated with these nanoshaped structures, wherein the half-pitch was 100 nm. The device significantly exceeded standard nanowire capacitor performance (by 90%) due to relative increase in surface area per unit projected area, enabled by the nanoshape. Going beyond the previous work, in this paper we explore the scaling of these nanoshaped structures to 10 nm half-pitch and below. At these scales a new “shape retention” resolution limit is observed due to polymer relaxation in imprint resists, which cannot be predicted with a linear elastic continuum model. An all-atom molecular dynamics model of the nanoshape structure was developed here to study this shape retention phenomenon and accurately predict the polymer relaxation. The atomistic framework is an essential modeling and design tool to extend the capability of imprint lithography to sub-10 nm nanoshapes. This framework has been used here to propose process refinements that maximize shape retention, and design template assist features (design for nanoshape retention) to achieve targeted nanoshapes.

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“…Here, we study the domain structure and the magnetic switching in the Permalloy (Fe 20 Ni 80 ) nanoscale magnetic junctions with different thicknesses by using micromagnetic simulations. It is found that both the 90-and 45-domain walls can be formed between the junctions and the wire arms depending on the thickness of the device.…”

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confidence: 99%

“…18,19 Recently, it has been reported that the magnetic switching induced by the spin-transfer torque (STT) can enable the junction to work as a STT-MRAM device. 20,21 There are also reports about the spin-polarized current that can induce the junction to generate spin waves. [22][23][24] It is found that the Permalloy junction has several metastable magnetization states, which can be used to store the information.…”

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confidence: 99%

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Magnetic domain wall engineering in a nanoscale permalloy junction

Wang

Zhang

et al. 2017

Applied Physics Letters

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Nanoscale magnetic junction provides a useful approach to act as the building block for magnetoresistive random access memories (MRAM), where one of the key issues is to control the magnetic domain configuration. Here, we study the domain structure and the magnetic switching in the Permalloy (Fe 20 Ni 80 ) nanoscale magnetic junctions with different thicknesses by using micromagnetic simulations. It is found that both the 90-degree and 45-degree domain walls can be formed between the junctions and the wire arms depending on the thickness of the device. The magnetic switching fields show distinct thickness dependencies with a broad peak varying from 7 nm to 22 nm depending on the junction sizes, and the large magnetic switching fields favor the stability of the MRAM operation.

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Micromagnetic study of spin-transfer-torque switching of a ferromagnetic cross towards multi-state spin-transfer-torque based random access memory

Cited by 13 publications

References 22 publications

Spin wave scattering and interference in ferromagnetic cross

Spin wave scattering and interference in ferromagnetic cross

Molecular dynamics modeling framework for overcoming nanoshape retention limits of imprint lithography

Magnetic domain wall engineering in a nanoscale permalloy junction

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