Magnetic anisotropy and reversal in epitaxial Fe/MgO(001) films

Zhan, Qingfeng; Vandezande, Stijn; Temst, Kristiaan; Haesendonck, C. Van

doi:10.1103/physrevb.80.094416

Cited by 53 publications

(53 citation statements)

References 29 publications

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“…It should be noticed that according to the reversal mechanism caused by two successive 90 o DW nucleations, the switching fields for the square loops are fitted by H c1 and H c3 , but not H c derived from the 180 o DW nucleation [20]. This is why we mark H c1 and H c3 as the switching fields for the square loop shown in Fig.…”

Section: Magnetization Reversal Mechanismmentioning

confidence: 97%

“…Considering a weak K u parallel to the [010] axis, we have previously shown that both the one-step and the two-step loops observed in epitaxial Fe/MgO(001) films are mediated by two successive or two separate 90 o DW nucleations 20,24 . The strength of K u and the DW nucleation energy ε 90 o can be evaluated by fitting the φ dependence of switching fields.…”

Section: Magnetization Reversal Mechanismmentioning

confidence: 99%

“…An effective field model, which considers the contributions to the effective field acting on the FM layer during magnetization reversal, was developed by Arenholz et al, to quantitatively interpret the complicated angular dependent switching fields 12 . On the other hand, both the multi-step loops and the angular dependent behaviors for the epitaxial Fe single layers can be described by a model based on domain wall (DW) nucleation 19,20 . Up till now, the evolution of magnetic reversal on t AFM , especially for the epitaxial systems, from the FM single layer (t AFM = 0) to the AFM/FM bilayers has not yet been well understood.…”

Section: Introductionmentioning

confidence: 99%

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Antiferromagnetic layer thickness dependence of the magnetization reversal in the epitaxial MnPd/Fe exchange bias system

2011

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We report an investigation on the antiferromagnetic layer thickness dependence of magnetization reversal in c-axis oriented MnPd/Fe epitaxial exchange biased bilayers. Several kinds of multi-step loops were observed for different samples measured at various field orientation. The evolution of the angular dependent magnetic behavior evolving from a representative Fe film to the exchange biased bilayers was revealed. With increase of the thickness of the antiferromagnetic layers, asymmetrically shaped loops and biased two-step loops are induced by exchange bias. Including the unidirectional anisotropy, a model based on the domain nucleation and propagation was developed, which can nicely describe the evolution of the magnetic behaviors for MnPd/Fe bilayers and correctly predicts the critical angles separating the occurrence of different magnetic switching processes. For fields applied along the bias direction, the 180 o magnetic reversal changes from two successive 90 o domain wall nucleations to a single 180 o domain wall nucleation at a critical thickness of the MnPd layer.

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Section: Magnetization Reversal Mechanismmentioning

confidence: 97%

Section: Magnetization Reversal Mechanismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Antiferromagnetic layer thickness dependence of the magnetization reversal in the epitaxial MnPd/Fe exchange bias system

2011

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“…4(c o ± 2δ DW nucleations [18]. The UMA component K u1 and the DW nucleation energies ǫ 90 o ±2δ can be evaluated by fitting the φ dependence of the experimental switching fields [8,17,18]. In Figs.…”

mentioning

confidence: 99%

Surface morphology and magnetic anisotropy of Fe/MgO(001) films deposited at oblique incidence

Zhan

Haesendonck

Vandezande

et al. 2009

Applied Physics Letters

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We have studied surface morphology and magnetic properties of Fe/MgO(001) films deposited at an angle varying between 0 o and 60 o with respect to the surface normal and with azimuth along the Fe [010] or the Fe[110] direction. Due to shadowing, elongated grains appear on the film surface for deposition at sufficiently large angle. X-ray reflectivity reveals that, depending on the azimuthal direction, films become either rougher or smoother for oblique deposition. For deposition along Fe[010] the pronounced uniaxial magnetic anisotropy (UMA) results in the occurrence of "reversed" two-step and of three-step hysteresis loops. For deposition along Fe[110] the growth-induced UMA is much weaker, causing a small rotation of the easy axes.Magnetic anisotropy of epitaxial films and its relationship to surface morphology have attracted much attention in recent years [1]. Both film properties are intimately related to the molecular beam epitaxy (MBE) deposition process. Oblique incidence deposition results via a self-shadowing effect [2,3] in the formation of grains in the plane of the film that are elongated perpendicular to the incident flux direction and with aspect ratio increasing at larger deposition angle with respect to the surface normal [4]. Consequently, an in-plane uniaxial magnetic anisotropy (UMA) with easy axis perpendicular to the incident flux direction is induced during growth of the magnetic films [4,5,6]. UMA was found to play an important role in determining the magnetization reversal in thin films of cubic systems [7,8]. Depending on the strength and orientation of the UMA, hysteresis curves with one, two and three steps are observed in various films at different field orientation. The appearance of the steps can be explained in terms of nucleation and propagation of domain walls (DWs) [8,9]. Consequently, understanding the influence of oblique incidence growth is very important because of its ability to control both magnetic anisotropy and surface morphology [10,11,12].Although shadowing effects have been studied in many magnetic systems, including Fe on MgO(001) [13] and Co on Cu(001) [14], the plane of oblique incidence was always kept parallel to the in-plane cubic easy axes of the magnetic layers. Here, we report on the influence of oblique deposition on the surface morphology and magnetic properties of Fe/MgO(001) films for deposition azimuth both along the Fe Fig. 1(c)). The elongated grains are believed to result from a redistribution of the incident flux due long-range attractive forces [15,16]. During evaporation the incident Fe atoms arrive preferentially on top of already formed grains rather than behind these grains. This shadowing effect is also observed for film deposition at 60 o with azimuth along [110]. The Fe grains on the surface are rhombic in shape with typical length of 15 nm and typical width of 6 nm (see Fig. 1(d)). Based on the STM images we conclude that the self-shadowing effect can be neglected for a deposition angle below 30 o . Moreover, the self-shadowing effect is...

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“…Nevertheless, the stepped loops for grains B and C may arise from the presence of two competing anisotropies, e.g., cubic ͑perhaps intrinsic to the expanded austenite͒ and uniaxial ͑e.g., due to residual strain͒ and a measuring field away from the easy-axes. 27,28 The crystalline orientation of grain A is close to ͗001͘, and relatively close to ͗111͘, and ͗101͘ for the grains B and C. The orientation of grain D ͑Ϸ͗214͒͘ is far from the directions of low indices. Thus, the magnetic and structural measurements indicate that the effective easy-axis is not along the ͗111͘ direction, as expected for fcc materials, 29 but lies along unusual directions as a result of interactions and multiple easy-axes.…”

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confidence: 76%

Out-of-plane magnetic patterning on austenitic stainless steels using plasma nitriding

Menéndez

Stinville

Tromas

et al. 2010

Applied Physics Letters

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A correlation between the grain orientation and the out-of-plane magnetic properties of nitrogen-enriched polycrystalline austenitic stainless steel surface is performed. Due to the competition between the magnetocrystalline anisotropy, the exchange and dipolar interactions, and the residual stresses induced by nitriding, the resulting effective magnetic easy-axis can lay along unusual directions. It is also demonstrated that, by choosing an appropriate stainless steel texturing, arrays of ferromagnetic structures with out-of-plane magnetization, embedded in a paramagnetic matrix, can be produced by local plasma nitriding through shadow masks.

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Magnetic anisotropy and reversal in epitaxial Fe/MgO(001) films

Cited by 53 publications

References 29 publications

Antiferromagnetic layer thickness dependence of the magnetization reversal in the epitaxial MnPd/Fe exchange bias system

Antiferromagnetic layer thickness dependence of the magnetization reversal in the epitaxial MnPd/Fe exchange bias system

Surface morphology and magnetic anisotropy of Fe/MgO(001) films deposited at oblique incidence

Out-of-plane magnetic patterning on austenitic stainless steels using plasma nitriding

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