Tailoring the magnetic and magneto-transport properties of Pd/Co multilayers and pseudo-spin valve antidots

Saldanha, D.R.; Dugato, Danian Alexandre; Mori, T. J. A.; Daudt, Natália de Freitas; Dorneles, L. S.; Denardin, Juliano C.

doi:10.1088/1361-6463/aad7ad

Cited by 8 publications

(4 citation statements)

References 29 publications

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“…The lowest value of the magnetic surface coverage ratio about 28.5-31.4 % has been obtained for Co, Py, and Co/Py bilayer antidot arrays samples with hole diameter 93 nm, 94 nm, and 95 nm, respectively, and interhole distance P =107 ± 3 nm, being lower than the ones reported in ref. [18][19][20]. The wide variation of hole diameter, W, and C has enabled us to study the full possible geometric parameters of Co, Py, and Co/Py bilayer antidot films deposited on nanoporous alumina membrane and their effect on the magnetic properties, especially the magnetic anisotropy.…”

Section: Resultsmentioning

confidence: 99%

Enhancement the perpendicular magnetic anisotropy of nanopatterned hard/soft bilayer magnetic antidot arrays for spintronic application

et al. 2020

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Development of perpendicular magnetic anisotropy (PMA) thin films is a requisite for many applications. In this work, we have illustrated the enhancement of the PMA of Hard (Co)/ Soft (Permalloy, Py) ferromagnetic bilayers by depositing them onto nanoporous anodic alumina membranes with different hole diameters varying in the range between 30 nm and 95 nm. A dramatic change in the hysteresis loops behaviour with hole size, D, and magnetic surface cover ratio parameters has been observed: (1) for samples with small antidot hole diameters, the in-plane (INP) hysteresis loops show single-step magnetic behaviour; (2) for D = 75 nm, the hysteresis loops of Co/Py and Py samples exhibit a multistep magnetic behaviour; (3) a decreasing coercivity in the INP hysteresis loops for antidot arrays samples with D > 75 nm has been detected as a consequence of the reduction of the in-plane magnetic anisotropy and the rising of the out-of-plane component. A crossover of magnetic anisotropy from the in-plane to out-of-plane for bilayer antidot samples has been observed for Co/Py ferromagnetic bilayers, favoured by the interfacial exchange coupling between the two ferromagnetic materials. These findings can be of high interest for the development of novel magnetic sensors and for perpendicular-magnetic recording patterned media based on template-assisted deposition techniques.

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Section: Resultsmentioning

confidence: 99%

Enhancement the perpendicular magnetic anisotropy of nanopatterned hard/soft bilayer magnetic antidot arrays for spintronic application

et al. 2020

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“…It seems that an increased OOP magnetization distribution was obtained for this sample with a 75 nm hole diameter related to the underlying surface morphology of the patterned substrate of the NPAAM. In fact, antidot (AD) thin films deposited on the top-surface of NPAAM templates reproduce the intrinsic surface roughness of the patterned templates, − but they also develop a crescent shape during the thin film deposition process, as sketched in Figure c. − These two morphological features can determine the magnetic anisotropy of the material. Thus, the magnetic moments between nanoholes remain aligned parallel within the film plane, while magnetic moments along the walls of the nanoholes are perpendicularly aligned to the film plane, as schematically shown in Figure c.…”

Section: Resultsmentioning

confidence: 99%

Tuning Nanohole Sizes in Ni Hexagonal Antidot Arrays: Large Perpendicular Magnetic Anisotropy for Spintronic Applications

Salaheldeen

Méndez

Vega

et al. 2019

ACS Appl. Nano Mater.

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Perpendicular magnetic anisotropy (PMA) in transition metal thin films offers a pathway for enabling the interesting physics of nanomagnetism and developing a wide range of spintronics applications. We demonstrate a simple method to obtain Ni thin films with PMA by depositing them onto nanoporous anodic alumina membranes (NPAAMs), with different pore diameters varying in the range between 32 ± 2 and 93 ± 1 nm. Thus, several sets of Ni antidot arrays thin films have been fabricated with different hole diameters, 35 nm ≤ d ≤ 89 nm, and fixed interhole distances, D int , around 103 ± 2 nm but reducing the edge-to-edge separation between adjacent antidots, (W = D int − d), and in two different situations, by considering that W is well above or below the layer thickness, t, of the thin film. The crossover from the in-plane magnetization to out of plane magnetization in a ferromagnetic thin film has been achieved by modifying only the nanopore size of the patterned anodic alumina template and the experimental results were supported by micromagnetic simulations performed with Mumax 3 code. A dramatic change in the coercivity, H C , dependence with d and W parameters has been observed with a critical nanohole diameter, d c , at which the appearance of the perpendicular magnetization is observed. The decreasing of the inplane coercivity for samples with d > 75 nm is due to the weakened of the in-plane magnetic anisotropy and the rising of the out of plane component. The effective perpendicular magnetic anisotropy energy density for Ni antidot thin film with d = 90 nm and t = 20 nm is around 1.44 erg/cm 2 , larger than that obtained by traditional approaches for Ni films with PMA (0.03−0.2 erg/cm 2 ). These findings point toward antidot thin films as novel routes to engineer the magnetic behavior of ferromagnetic metal with large PMA, which might entail a milestone for future applications in bit patterned magneto-optic perpendicular recording media and spintronic devices.

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“…The lowest value of the magnetic surface coverage ratio,

(see ref. [ 49 ] for further details), was obtained for CoO/Co ML antidot array samples with hole diameter 94 ± 3 nm (see Table 1 ), being lower than for other systems obtained using similar techniques [ 50 , 51 , 52 ]. The large variation of the magnetic surface coverage allowed us to investigate the influence of the geometric parameters of CoO/Co ML antidot films deposited on NAA on the exchange bias effect and the magnetic anisotropy.…”

Section: Resultsmentioning

confidence: 76%

Enhancement of Exchange Bias and Perpendicular Magnetic Anisotropy in CoO/Co Multilayer Thin Films by Tuning the Alumina Template Nanohole Size

et al. 2022

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The interest in magnetic nanostructures exhibiting perpendicular magnetic anisotropy and exchange bias (EB) effect has increased in recent years owing to their applications in a new generation of spintronic devices that combine several functionalities. We present a nanofabrication process used to induce a significant out-of-plane component of the magnetic easy axis and EB. In this study, 30 nm thick CoO/Co multilayers were deposited on nanostructured alumina templates with a broad range of pore diameters, 34 nm ≤ Dp ≤ 96 nm, maintaining the hexagonal lattice parameter at 107 nm. Increase of the exchange bias field (HEB) and the coercivity (HC) (12 times and 27 times, respectively) was observed in the nanostructured films compared to the non-patterned film. The marked dependence of HEB and HC with antidot hole diameters pinpoints an in-plane to out-of-plane changeover of the magnetic anisotropy at a nanohole diameter of ∼75 nm. Micromagnetic simulation shows the existence of antiferromagnetic layers that generate an exceptional magnetic configuration around the holes, named as antivortex-state. This configuration induces extra high-energy superdomain walls for edge-to-edge distance >27 nm and high-energy stripe magnetic domains below 27 nm, which could play an important role in the change of the magnetic easy axis towards the perpendicular direction.

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Tailoring the magnetic and magneto-transport properties of Pd/Co multilayers and pseudo-spin valve antidots

Cited by 8 publications

References 29 publications

Enhancement the perpendicular magnetic anisotropy of nanopatterned hard/soft bilayer magnetic antidot arrays for spintronic application

Enhancement the perpendicular magnetic anisotropy of nanopatterned hard/soft bilayer magnetic antidot arrays for spintronic application

Tuning Nanohole Sizes in Ni Hexagonal Antidot Arrays: Large Perpendicular Magnetic Anisotropy for Spintronic Applications

Enhancement of Exchange Bias and Perpendicular Magnetic Anisotropy in CoO/Co Multilayer Thin Films by Tuning the Alumina Template Nanohole Size

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