Cascade-like signal propagation in chains of concave nanomagnets

Lambson, Brian; Gu, Zhiyong; Carlton, David; Dhuey, Scott; Schöll, A.; Doran, Andrew; Young, A. T.; Bokor, Jeffrey

doi:10.1063/1.3703591

Cited by 19 publications

(12 citation statements)

References 13 publications

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“…The process reported here is a common issue in NML operation, where the switching of nanomagnetic bits is very sensitive to small variations in coupling between them. [ 1,2,21 ] In Adv. Mater.…”

Section: Resultsmentioning

confidence: 99%

Magnetic State of Multilayered Synthetic Antiferromagnets during Soliton Nucleation and Propagation for Vertical Data Transfer

Fernández-Pacheco

Steinke

Mahendru

et al. 2016

Adv Materials Inter

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data, but also allows complex sequential logic operations using logic gates to be performed. [ 3 ] The nonvolatility of this technology, [ 1 ] its potential ultra-low power consumption, [ 4 ] the possibility to address data using spin-transfer-torque [ 5 ] or the spin-Hall effect, [ 6 ] the robustness of some designs against data transfer errors caused by thermal fl uctuations, [ 7 ] and the high speeds of data transfer [ 8 ] have identifi ed NML as a promising candidate for future computing technologies. One of the main unresolved challenges for NMLbased technology is data transfer in the vertical direction, a necessary step toward 3D spintronic systems. [ 9 ] We have recently extended the idea of using solitons in coupled magnets for vertical (out-of-plane) data transfer. [10][11][12][13][14][15][16][17] For this, multilayered synthetic antiferromagnets (SAFs) formed by N ferromagnetic layers and coupled via Rudderman-Kittel-Kasuya-Yosida (RKKY) interactions through N -1 nonmagnetic interlayers were used ( Figure 1 ). We have shown that in an even-N -layer system, we can control the nucleation and propagation of solitons by exploiting the surface spinfl op transition (SSF): [ 10 ] an edge layer thicker than the others acts as a gate, switching independently from the rest at the SSF fi eld and nucleating a soliton at the bottom of the system. When the fi eld is relaxed, the RKKY coupling between layers causes the upper layers to switch in a cascade-like manner, propagating the soliton upward throughout the spin interconnector until it gets expelled. The fi nal state at remanence is the contrary antiparallel state than at the start, a consequence of all layers switching, including the top output layer where information is read. This data transfer is analogous to some previously reported NML schemes, [ 1,2 ] but in this case along the vertical direction. Using perpendicularly magnetized (Ising) SAFs, it has also been shown that the propagation of solitons can be performed synchronously with an external magnetic fi eld when the properties of the SAF are tuned in a ratchet fashion, with the system acting as a soliton shift register. [ 14,15,17 ] In this work, we explore in detail the behavior of SAFs under external magnetic fi elds during soliton nucleation and asynchronous propagation [ 10,13 ] by using the Kerr effect, magnetoresistance, polarized neutron refl ectivity (PNR) measurements, and macrospin simulations.Magnetic solitons in multilayered synthetic antiferromagnets (SAFs) have been recently proposed as data carriers for vertical data transfer, constituting a promising approach for 3D spintronic systems. Here, the nucleation and propagation of solitons in CoFeB/Ru SAFs are investigated under external magnetic fi elds by magnetooptical Kerr effect (MOKE), magnetoresistance (MR), and polarized neutron refl ectivity (PNR) measurements. By comparing MOKE and MR measurements with macrospin simulations, the key steps of the mechanism behind soliton nucleation, triggered by the surface spin-fl op transition and ...

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Section: Resultsmentioning

confidence: 99%

Magnetic State of Multilayered Synthetic Antiferromagnets during Soliton Nucleation and Propagation for Vertical Data Transfer

Fernández-Pacheco

Steinke

Mahendru

et al. 2016

Adv Materials Inter

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“…Lack of robustness is a key issue for NML, 4 and there have been only a few studies 5,6 made so far to improve it. CMOSbased logic devices have an error probability on the order of 10 À17 .…”

Section: Introductionmentioning

confidence: 99%

Error analysis for ultra dense nanomagnet logic circuits

Shah

Csaba

Niemier

et al. 2015

Journal of Applied Physics

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Dependency of errors in nanomagnet logic datalines on the dipole coupling strength is investigated. Evolution of different types of errors at different coupling strengths is studied. Dipole coupling strength in datalines is varied by changing the inter-magnet spacing from 30 nm to 10 nm and the aspect ratios of the 20-nm-thick Supermalloy (Ni 79 Fe 16 Mo 5 ) dots from 90 Â 60 nm 2 to 120 Â 60 nm 2 . An error rate improvement up to 46% is observed for inter-magnet space reduction from 30 nm to 10 nm. Error rates in datalines with larger spacing are dominated by premature switching, whereas a new type of error, due to the stronger influence of the driver magnets, dominates in datalines with tighter (sub-20-nm) spacing. For same spacing, datalines with lower aspect ratio magnets show higher error rates compared to those with higher aspect ratio. V C 2015 AIP Publishing LLC.

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“…For example, a biaxial anisotropy was proposed to enhance the hard axis stability. 4 Alternatively, different shaped nanomagnets, such as S-shaped, 5 edge-slanted, 6 and concaved 7 elements, have been proposed. Even though these designs facilitate signal propagation to some extent, they all rely on a highly accurate clocking field alignment.…”

Section: Introductionmentioning

confidence: 99%

Highly stable signal propagation in a consecutively tuned nanomagnet array

Krishnan

2013

Journal of Applied Physics

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A key function of magnetic quantum-dot cellular automata (MQCA) is signal propagation in the nanomagnet array, for which a clocking field is required. However, the misalignment of the clocking field and the resultant low stability for signal propagation is one of the main challenges for its application. Here, we modeled and fabricated a progressively shape-tuned nanomagnet array combined with a reversal clocking field with progressively reduced amplitude. Based on micromagnetic simulations, Fe nanomagnet arrays were fabricated by electron beam lithography and their magnetization states characterized by magnetic force microscopy demonstrated correct signal propagation against clocking field misalignment up to 65. Furthermore, cascade-like signal propagation was observed. This novel design provides high stability and directional control in signal propagation within the nanomagnet array and potentially paves the way for addressing the misalignment issue in MQCA structures. V

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Cascade-like signal propagation in chains of concave nanomagnets

Cited by 19 publications

References 13 publications

Magnetic State of Multilayered Synthetic Antiferromagnets during Soliton Nucleation and Propagation for Vertical Data Transfer

Magnetic State of Multilayered Synthetic Antiferromagnets during Soliton Nucleation and Propagation for Vertical Data Transfer

Error analysis for ultra dense nanomagnet logic circuits

Highly stable signal propagation in a consecutively tuned nanomagnet array

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