Polarized neutron reflectometry studies of magnetic oxidic Fe3O4/NiO and Fe3O4/CoO multilayers

Ball, A.R.; Fredrikze, H.; Lind, D. M.; Wolf, R.M.; Bloemen, P.J.H.; Rekveldt, M.Th.; Zaag, P. J. van der

doi:10.1016/0921-4526(95)00954-x

Cited by 18 publications

(13 citation statements)

References 14 publications

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“…The coercivity is related to the anisotropy constants and the saturation magnetization of the FM materials and can be roughly expressed as H C / K FM /M FM , 60 at the same time, the H E / (K FM A FM ) 1/2 /M FM t FM when the domain wall formed on the FM side of the interface; 3 thus, the relationship H C / H E 2 can be obtained, which is well expressed as an inset (right) of Fig. 4(b), indicating the domain wall formed in the FM layer proposed by Ball et al 19,20 and the tunability of the exchange bias by the Verwey transition; moreover, Ijiri et al 61 also found that the CoO AFM ordering is long-range and propagates coherently through the intervening Fe 3 O 4 layer in Fe 3 O 4 /CoO superlattices. van der Zaag et al 32 calculated the low-temperature unidirectional…”

Section: Resultsmentioning

confidence: 64%

Mediating exchange bias by Verwey transition in CoO/Fe3O4 thin film

Liu

Zhang

et al. 2018

Journal of Applied Physics

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We report the tunability of the exchange bias effect by the first-order metal-insulator transition (known as the Verwey transition) of Fe 3 O 4 in CoO (5 nm)/Fe 3 O 4 (40 nm)/MgO (001) thin film. In the vicinity of the Verwey transition, the exchange bias field is substantially enhanced because of a sharp increase in magnetocrystalline anisotropy constant from high-temperature cubic to lowtemperature monoclinic structure. Moreover, with respect to the Fe 3 O 4 (40 nm)/MgO (001) thin film, the coercivity field of the CoO (5 nm)/Fe 3 O 4 (40 nm)/MgO (001) bilayer is greatly increased for all the temperature range, which would be due to the coupling between Co spins and Fe spins across the interface. Published by AIP Publishing. https://doi.

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Section: Resultsmentioning

confidence: 64%

Mediating exchange bias by Verwey transition in CoO/Fe3O4 thin film

Liu

Zhang

et al. 2018

Journal of Applied Physics

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“…These results are in agreement with previous works. 24,25 The magnetic hysteresis loops of the 50-, 25-, 15-, and 8-nm-thick Fe 3 O 4 ͑111͒ films have also been measured at room temperature up to 2 T using a VSM. The field was applied along the ͓1120͔ axis in plane and along the [0001] axis out of plane of the ␣-Al 2 O 3 ͑0001͒ substrate (see Fig.…”

Section: Magnetic Behaviormentioning

confidence: 99%

Thickness dependence of anomalous magnetic behavior in epitaxial Fe3O4(111) thin films: Effect of density of antiphase boundaries

et al. 2004

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We study the magnetic behavior of Fe 3 O 4 ͑111͒ thin films with thicknesses between 5 nm and 50 nm. The films are epitaxially grown on ␣-Al 2 O 3 ͑0001͒ single crystals by atomic-oxygen-assisted molecular beam epitaxy. The Fe 3 O 4 ͑111͒ thin films exhibit high structural order with sharp interfaces and low roughness and exhibit a Verwey transition for thicknesses above 8 nm. However, the samples have magnetic properties that deviate from the bulk ones. The magnetic moment varies between 2.4 B for 5-nm-thick film and 3.2 B for 50-nm-thick film in a field of 1.2 T, which is lower than that of bulk samples (4.1 B /Fe 3 O 4 formula). Still the magnetic saturation is never reached, even in fields as large as 2 T. The thinner the film, the slower the approach to saturation. Structural analysis, performed using high-resolution transmission electron microscopy, reveals the presence of antiphase boundaries (APB's), the density of which decreases when the thickness increases. Using a model of ferromagnetic domains separated by antiferromagnetically sharp interfaces, we show that the slow approach to saturation observed in the films as a function of thickness is driven by the APB density.

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“…Recently, nanocrystalline CoO has been reported as a photocatalyst for water splitting by visible-light irradiation [16], and both CoO and Co 3 O 4 have potential applications in devices such as battery electrodes [17], gas sensors [15,[18][19][20], solar-selective absorbers [21] and spintronic devices through the formation of exchange bias layers [22]. Epitaxial thin films or layers of these cobalt oxides have been grown by several methods, including PLD [23][24][25], molecular beam epitaxy [26][27][28][29], atomic layer deposition [30][31][32], chemical vapor deposition [33], sol-gel [34], thermal evaporation [35], and surface oxidation of metallic cobalt [36,37]. However, the previously reported epitaxial growth requires relatively high substrate temperature of at least 138 • C or post-annealing for oriented crystallization [30].…”

Section: Introductionmentioning

confidence: 99%