X-ray analysis of oxygen-induced perpendicular magnetic anisotropy in trilayers

Manchon, Aurélien; Pizzini, S.; Vogel, Jan; Uhlíř, Vojtěch; Lombard, L.; Ducruet, C.; Auffret, S.; Rodmacq, B.; Diény, B.; Hochstrasser, M.; Panaccione, G.

doi:10.1016/j.jmmm.2008.02.131

Cited by 32 publications

(40 citation statements)

References 17 publications

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“…This interfacial PMA is generally interpreted in terms of a strong hybridization effect between Fe (Co) 3d orbital pointing toward the interface (viz. d [11,12,[19][20][21]. This hybridization combined with spin-orbit coupling is suggested to result in observed PMA.…”

Section: Introductionmentioning

confidence: 86%

In situsmall-angle x-ray and nuclear resonant scattering study of the evolution of structural and magnetic properties of an Fe thin film on MgO (001)

Sharma

Gupta

et al. 2015

Phys. Rev. B

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Growth of magnetron sputtered Fe films on clean single crystalline MgO (001) substrate has been studied using in situ grazing incidence small angle x-ray scattering (GISAXS) and grazing incidence nuclear resonant scattering (GINRS) measurements. While GISAXS provides information about morphological changes, GINRS provides information about structural and magnetic properties, thus making it possible to correlate the evolution of magnetic properties with that of morphology and structure of the film. The film exhibits a Volmer-Weber type growth, with percolation transition occurring around 2 nm film thickness. Presence of a finite quadrupole splitting, as seen in GINRS measurements, suggests a significant distortion from cubic symmetry up to a film thickness of 3.5 nm, which can be attributed to hybridization between Fe 3d and O 2p orbitals at the interface as well as in-plane tensile strain induced as a result of coalescence of islands. Initially Fe islands exhibit superparamagnetic relaxation, while finite magnetic moment appears upon formation of macroscopic percolation islands. The film exhibits a weak perpendicular magnetic anisotropy (PMA), which vanishes concurrently with disappearance of structural distortion, suggesting that the observed PMA at least partly originates from inherent strain in the film. No presence of any known oxide of Fe was detected at the interface. More precise information about topological and magnetic structure of the interfaces between Fe and MgO layers is obtained using combined x-ray reflectivity and nuclear resonance reflectivity measurements on a 57 Fe/MgO multilayer. Measurements show that about two monolayers of Fe at the interface have a reduced hyperfine field, providing evidence for hybridization with O atoms, as predicted by theory.

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Section: Introductionmentioning

confidence: 86%

In situsmall-angle x-ray and nuclear resonant scattering study of the evolution of structural and magnetic properties of an Fe thin film on MgO (001)

Sharma

Gupta

et al. 2015

Phys. Rev. B

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“…31 We point out that the situation of a "pure" interface is the most stable one, as observed in annealing experiments. 28,29 The most stable location for the oxygen atoms is on top of metal ions due to the strong overlap between Fe-3d and O-2p orbitals. Correlatively, it is interesting to note that this structural configuration also yields the spin filtering phenomenon based on Bloch state symmetry leading to high TMR values.…”

Section: Methodsmentioning

confidence: 99%

“…24,25 This result is quite general and has been observed in both crystalline (MgO) and amorphous (AlOx) barriers, using both natural or plasma oxidation. 26,27 The PMA could be dramatically improved under annealing, 10,28,29 and x-ray photoemission spectroscopy has demonstrated that the PMA could be correlated without ambiguity with the presence of oxygen atoms at the interface. 26,27 In fact, a correlation between PMA and oxidation conditions has been demonstrated for a wide range of FM|MOx including those based on Co x Fe 1−x , thus indicating that the phenomenon is quite general at interfaces between magnetic transition metals and oxygen-terminated oxides.…”

Section: Introductionmentioning

confidence: 99%

First-principles investigation of the very large perpendicular magnetic anisotropy at Fe|MgO and Co|MgO interfaces

et al. 2011

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The perpendicular magnetic anisotropy (PMA) arising at the interface between ferromagnetic transition metals and metallic oxides was investigated via first-principles calculations. In this work very large values of PMA, up to 3 erg/cm 2 , at Fe|MgO interfaces are reported, in agreement with recent experiments. The origin of PMA is attributed to overlap between O-p z and transition metal d z 2 orbitals hybridized with d xz(yz) orbitals with stronger spin-orbit coupling-induced splitting around the Fermi level for perpendicular magnetization orientation. Furthermore, it is shown that the PMA value weakens in the case of over-or underoxidation due to the fact that oxygen p z and transition metal d z 2 orbital overlap is strongly affected by disorder, in agreement with experimental observations in magnetic tunnel junctions.

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“…The films were deposited on a Si/SiO 2 substrate by magnetron sputtering. Samples were oxidized in situ by oxygen plasma in order to induce PMA [19]. Magnetization reversal was studied using magneto-optical Kerr microscopy.…”

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confidence: 99%

Chirality-Induced Asymmetric Magnetic Nucleation inPt/Co/AlOxUltrathin Microstructures

et al. 2014

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The nucleation of reversed magnetic domains in Pt/Co/AlOx microstructures with perpendicular anisotropy was studied experimentally in the presence of an in-plane magnetic field. For large enough in-plane field, nucleation was observed preferentially at an edge of the sample normal to this field. The position at which nucleation takes place was observed to depend in a chiral way on the initial magnetization and applied field directions. A quantitative explanation of these results is proposed, based on the existence of a sizable Dzyaloshinskii-Moriya interaction in this sample. Another consequence of this interaction is that the energy of domain walls can become negative for in-plane fields smaller than the effective anisotropy field. [5]. In the latter case, the transcription of the chirality from the atomic scale to the macroscopic scale of textures may be impeded by the existence of an anisotropy. This is exemplified in liquid crystals, where under a DC magnetic or electric field that induces anisotropy, the cholestericnematic transition takes place [4]. Thus, the detection and quantification of a chiral interaction when it is too weak to give rise to a global chiral texture is difficult.Magnetism is another prominent field where chiral textures are considered. A chiral magnetic interaction indeed exists, namely an anti-symmetric exchange called Dzyaloshinskii-Moriya interaction (DMI) [5, 6], that is allowed when central symmetry is broken. In many compounds having this property, especially the cubic B20 structures with depressed magnetic anisotropy, chiral textures like homochiral spin spirals or 2D skyrmion lattices have been observed, both in reciprocal [7] and in real space [8]. Another class of chiral magnetic systems has recently appeared, namely the few atomic layer thick samples grown on an underlayer with large spinorbit interaction, showing structural inversion asymmetry and perpendicular magnetic anisotropy (PMA) [9][10][11][12]. In these systems, PMA is very strong so that chiral spin spirals are not stable, and as a result DMI has remained unnoticed for about 20 years. However, at magnetic edges like a domain wall (DW) separating two uniformly magnetized domains or at physical edges in a microstructure, the competition of chiral interaction with anisotropy is modified. Indeed, the peculiarities of field and current-induced dynamics of domain walls in such samples [13][14][15] have been found to be consistent with a chiral texture localized on the DW, deriving from the presence of interface-induced DMI [16]. These local chiral magnetization textures, that appear as Néel walls of a fixed chirality, have also been observed recently by lowenergy electron microscopy [17,18], on samples with wide domain walls.In this Letter we show that chiral interactions can also be detected at the edges of a microstructure: in the presence of an additional in-plane field, nucleation of reversed domains takes place preferentially at one edge of the sample, oriented perpendicular to this field. The side at which nucle...

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X-ray analysis of oxygen-induced perpendicular magnetic anisotropy in trilayers

Cited by 32 publications

References 17 publications

In situsmall-angle x-ray and nuclear resonant scattering study of the evolution of structural and magnetic properties of an Fe thin film on MgO (001)

In situsmall-angle x-ray and nuclear resonant scattering study of the evolution of structural and magnetic properties of an Fe thin film on MgO (001)

First-principles investigation of the very large perpendicular magnetic anisotropy at Fe|MgO and Co|MgO interfaces

Chirality-Induced Asymmetric Magnetic Nucleation inPt/Co/AlOxUltrathin Microstructures

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