Controlling the magnetization reversal in exchange-biased Co/CoO elongated nanorings

Tripathy, D.; Adeyeye, A. O.; Singh, Navab; Stamps, R. L.

doi:10.1088/0957-4484/20/1/015304

Cited by 17 publications

(18 citation statements)

References 21 publications

(23 reference statements)

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“…When the nanorings are field cooled at varying angles with respect to the major axis, the energetically favorable direction set in the CoO layer along the major axis due to shape anisotropy, is altered due to competition with the unidirectional anisotropy induced by field cooling. Applying the external field along the major axis will try to reorient the spins in the Co layer at different angles from the field cooling direction, and thus result in an increase in the exchange energy of the system [10]. We have thus shown that by adjusting the field cooling angle, the competition between shape anisotropy and unidirectional anisotropy was exploited to engineer the easy axis of the nanorings away from the intrinsic major axis.…”

Section: Exchange Biased Co/coo Nanoringsmentioning

confidence: 97%

Patterned ferromagnetic and exchange biased nanostructures

Adeyeye

Tripathy

2009

2009 International Conference on Electromagnetics in Advanced Applications

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Exchange bias effects have been systematically investigated in Co (25 nm)/CoO (5 nm)/Cu (2 nm) nanoring arrays and Cu (10 nm)/NiFe (30 nm)/IrMn (30 nm)/Cu (2 nm) nanoscale antidot arrays. For the nanorings, the magnetization reversal mechanism and magnitude of exchange bias field HE is strongly dependent on the strength and orientation of the cooling field relative to the major axis of the nanorings. The antidot arrays exhibit asymmetric hysteresis loops and show larger HE values as compared to the continuous film. This is attributed to reduced interactions in the NiFe layer and constraints imposed on the IrMn domain size by the antidots.

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Section: Exchange Biased Co/coo Nanoringsmentioning

confidence: 97%

Patterned ferromagnetic and exchange biased nanostructures

Adeyeye

Tripathy

2009

2009 International Conference on Electromagnetics in Advanced Applications

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“…Since the discovery of EB in Co/CoO particles over 50 years ago, 9 it has been found in a variety of different systems with FM/AFM interfaces, including core-shell nanoparticles, [10][11][12] thin film systems, 3,5,13,14 lithographed nanostructures, [15][16][17][18] and (more recently) in high aspect ratio core-shell nanotubes (NTs). 19 The latter have attracted much interest due to their potential applications in nanoelectronic devices, catalysis, high-density recording media, and drug delivery.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of the training effect in electrodeposited Co/CoO nanotubes

Proença

Ventura

Sousa

et al. 2013

Journal of Applied Physics

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High aspect ratio Co/CoO nanotubes (NTs) were obtained by potentiostatic electrodeposition of Co inside nanoporous alumina templates followed by the natural oxidation of their inner walls. Magnetic measurements performed at low temperatures after field cooling the samples from above its blocking temperature (T B $ 220 K), evidenced the existence of exchange bias (EB) coupling between the Co ferromagnetic outer wall and the CoO antiferromagnetic inner wall of the NTs. A decrease in the magnitude of the EB field was measured at T < T B when cycling the Co/CoO NT arrays through consecutive hysteresis loops. This decrease is known as the training effect (TE) and is here studied in the 6 K T < T B temperature range. The TE was fitted using the recursive Binek formula, giving small values for the characteristic decay rate of the training behavior, and evidencing a decrease of EB with increasing antiferromagnetic layer thickness. A phenomenological theory for the temperature dependence of the TE in exchange biased systems was applied for the first time to core-shell nanotubular structures. The good agreement obtained between the experimental results and the theoretical data, provided a strong confirmation of the qualitative correctness of the spin configuration relaxation model used in these systems.

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“…11 However, so far, reported work on EB rings is very limited. [12][13][14][15] Exchange bias induced asymmetric magnetization behavior along the bias direction has been observed in magnetic ring structures, 16 but the detailed mechanism of magnetic reversal is not well understood.…”

Section: Introductionmentioning

confidence: 99%

Thickness-dependent magnetization reversal behavior of lithographic IrMn/Fe ring structures

Hou

Krishnan

2012

Journal of Applied Physics

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Magnetization reversal and magnetoresistance behavior of perpendicularly magnetized [Co/Pd]4/Au/[Co/Pd]2 nanowires J. Appl. Phys. 112, 073902 (2012) Magnetization reversal in multisegmented nanowires: Parallel and serial reversal modes Appl. Phys. Lett. 101, 122412 (2012) Electric field-induced magnetization reversal in a perpendicular-anisotropy CoFeB-MgO magnetic tunnel junction Appl. Phys. Lett. 101, 122403 (2012) The magnetic Y-branch nanojunction: Domain-wall structure and magneto-resistance Appl.We systematically studied the effect of exchange bias (EB) on the magnetization reversal behavior in lithographic IrMn/Fe rings and their unbiased Fe counterparts, with the thickness of the Fe layer, t Fe , varying from 10 to 80 nm. For unbiased and exchange biased rings, an evolution in the shape of the hysteresis loop from single-step to double-step is observed as t Fe increases. However, for EB rings, this transition happens at larger thickness, which is attributed to the uniaxial anisotropy induced by exchange bias in the Fe layer. The strength of the magnetic anisotropy induced by exchange bias is investigated by fitting the angular dependence of the exchange bias field H eb at different Fe thickness.

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Controlling the magnetization reversal in exchange-biased Co/CoO elongated nanorings

Cited by 17 publications

References 21 publications

Patterned ferromagnetic and exchange biased nanostructures

Patterned ferromagnetic and exchange biased nanostructures

Temperature dependence of the training effect in electrodeposited Co/CoO nanotubes

Thickness-dependent magnetization reversal behavior of lithographic IrMn/Fe ring structures

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