X-ray magnetic circular dichroism study of epitaxial magnetite ultrathin film on MgO(100)

Liu, W. Q.; Song, M. Y.; Maltby, N. J.; Li, S. P.; Lin, Jia-Chun; Samant, Mahesh G.; Parkin, Stuart S. P.; Benčok, P.; Steadman, P.; Dobrynin, A. N.; Xu, Yongbing; Zhang, R.

doi:10.1063/1.4916296

Cited by 12 publications

(8 citation statements)

References 40 publications

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“…Within the probing depth of XAS and XMCD of 3 nm from the sample surface, the interfacial regions are detected, including the capping MgO layer. The intensities of Fe 2+ and Fe 3+ in O h are almost similar to those of previous studies of XMCD in Fe 3 O 4 [34][35][36][37], meaning that the Fe 3 O 4 with stoichiometric B site is synthesized, but the Verwey transition is absent in Sample 1. Since the Verwey transition has been reported to be very sensitive to oxygen composition [38,39], the O 2 partial pressure significantly influences the transport of Fe 3 O 4 .…”

Section: Resultssupporting

confidence: 87%

Large Inverse Tunnel Magnetoresistance in Magnetic Tunnel Junctions with an Fe3O4 Electrode

et al. 2021

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Spinel-type magnetite Fe 3 O 4 is predicted to be a half-metal material with negative spin polarization. However, magnetic tunnel junctions (MTJs) using an Fe 3 O 4 electrode exhibit a small tunnel magnetoresistance (TMR) effect, the sign of which has not been established experimentally. The development of Fe 3 O 4 as an excellent TMR material requires a better understanding of the characteristics of the interface and the phase transition of Fe 3 O 4 called the Verwey transition. We fabricate MTJs using epitaxial Fe 3 O 4based stacks on MgO(001) substrates and find a large inverse TMR ratio of −55.8% at 80 K, which corresponds to 126% by the optimistic definition of the TMR ratio. The temperature dependence of the TMR ratio is significantly affected by the Verwey transition. Moreover, we investigate the dependence of TMR on oxygen partial pressure during Fe 3 O 4 deposition. It is found that the magneto-transport properties of the MTJs show different behaviors depending on the oxygen partial pressure because the Verwey transition is sensitive to the oxygen concentration. Furthermore, the electronic and magnetic properties at the interfacial regions are investigated by x-ray magnetic spectroscopy and first-principles calculation. These findings greatly support the use of Fe 3 O 4 in spintronic devices and should lead to further developments in oxide spintronics.

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Section: Resultssupporting

confidence: 87%

Large Inverse Tunnel Magnetoresistance in Magnetic Tunnel Junctions with an Fe3O4 Electrode

et al. 2021

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“…The element-specific spin ( m spin ) and orbital ( m orb ) moments of the two epitaxial thin films were extracted by applying the sum rules − to the integrated XMCD and summed XAS spectra of the Fe, Co, and Ni L 2,3 -edges. The effective number of valence holes, n h , was obtained by integrating over the unoccupied density of 3d states, ρ( E ), based on the sample configurations, and the results are 3.19, 2.29, 2.50, and 1.45 for the stabilizing Fe, interfacial Co, stabilizing Co, and interfacial Ni atoms, respectively, in agreement with the previous reports on the Fe, Co, and Ni thin films. ,, In order to exclude the nonmagnetic part of the XAS spectra, an arctangent-based step function was used to fit the threshold. − As can be seen from Figure e,f, the integration (dashed line) of both XMCD and summed XAS spectra becomes flat within the measured range, providing a proper background offset. The sum-rule-derived values for m spin are collected in Table , from which a significant contrast can be seen between the Co/GaAs and Ni/GaAs interfaces with identical thicknesses.…”

supporting

confidence: 83%

Probing the Buried Magnetic Interfaces

Liu

Zhou

Chen

et al. 2016

ACS Appl. Mater. Interfaces

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Understanding magnetism in ferromagnetic metal/semiconductor (FM/SC) heterostructures is important to the development of the new-generation spin field-effect transistor. Here, we report an element-specific X-ray magnetic circular dichroism study of the interfacial magnetic moments for two FM/SC model systems, namely, Co/GaAs and Ni/GaAs, which was enabled using a specially designed FM1/FM2/SC superstructure. We observed a robust room temperature magnetization of the interfacial Co, while that of the interfacial Ni was strongly diminished down to 5 K because of hybridization of the Ni d(eg) and GaAs sp(3) states. The validity of the selected method was confirmed by first-principles calculations, showing only small deviations (<0.02 and <0.07 μB/atom for Co/GaAs and Ni/GaAs, respectively) compared to the real FM/SC interfaces. Our work proved that the electronic structure and magnetic ground state of the interfacial FM2 is not altered when the topmost FM2 is replaced by FM1 and that this model is applicable generally for probing the buried magnetic interfaces in the advanced spintronic materials..

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“…11 (f) adopted from 11,36 ). In the mixed II / III Fe 3 O 4 the low energy peak is higher and wider due to the presence of the O h Fe II ions 29,44 . The net magnetization in ferrimagnetic iron oxides results from the antiparallel alignment of magnetic moments at the octahedral and tetrahedral Fe sites.…”

Section: X-ray Absorption Spectroscopy and Magnetic Circular Dichroismmentioning

confidence: 99%

Tunable polymorphism of epitaxial iron oxides in the four-in-one ferroic-on-GaN system with magnetically ordered α-, γ-, ɛ−Fe2O3 , and Fe3
Korovin¹,
Gastev²,
Волков³
et al. 2018
Phys. Rev. Materials
23
2
23
0
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Hybridization of semiconducting and magnetic materials into a single heterostructure is believed to be potentially applicable to the design of novel functional spintronic devices. In the present work we report epitaxial stabilization of four magnetically ordered iron oxide phases (Fe 3 O 4 , γ-Fe 2 O 3 , α-Fe 2 O 3 and most exotic metastable ε-Fe 2 O 3 ) in the form of nanometer sized single crystalline films on GaN(0001) surface. The epitaxial growth of as many as four distinctly different iron oxide phases is demonstrated within the same singletarget Laser MBE technological process on a GaN semiconductor substrate widely used for electronic device fabrication. The discussed iron oxides belong to a family of simple formula magnetic materials exhibiting a rich variety of outstanding physical properties including peculiar Verwey and Morin phase transitions in Fe 3 O 4 and α-Fe 2 O 3 and multiferroic behavior in metastable magnetically hard ε-Fe 2 O 3 ferrite. The physical reasons standing behind the nucleation of a particular phase in an epitaxial growth process deserve interest from the fundamental point of view. The practical side of the presented study is to exploit the tunable polymorphism of iron oxides for creation of ferroic-on-semiconductor heterostructures usable in novel spintronic devices. By application of a wide range of experimental techniques the surface morphology, crystalline structure, electronic and magnetic properties of the single phase iron oxide epitaxial films on GaN have been studied. A comprehensive comparison has been made to the properties of the same ferrite materials in the bulk and nanostructured form reported by other research groups.

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X-ray magnetic circular dichroism study of epitaxial magnetite ultrathin film on MgO(100)

Cited by 12 publications

References 40 publications

Large Inverse Tunnel Magnetoresistance in Magnetic Tunnel Junctions with an Fe3O4 Electrode

Large Inverse Tunnel Magnetoresistance in Magnetic Tunnel Junctions with an Fe3O4 Electrode

Probing the Buried Magnetic Interfaces

Tunable polymorphism of epitaxial iron oxides in the four-in-one ferroic-on-GaN system with magnetically ordered α-, γ-, ɛ−Fe2O3 , and Fe3
Korovin¹,
Gastev²,
Волков³
et al. 2018
Phys. Rev. Materials
23
2
23
0
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X-ray magnetic circular dichroism study of epitaxial magnetite ultrathin film on MgO(100)

Cited by 12 publications

References 40 publications

Large Inverse Tunnel Magnetoresistance in Magnetic Tunnel Junctions with an Fe3O4 Electrode

Large Inverse Tunnel Magnetoresistance in Magnetic Tunnel Junctions with an Fe3O4 Electrode

Probing the Buried Magnetic Interfaces

Tunable polymorphism of epitaxial iron oxides in the four-in-one ferroic-on-GaN system with magnetically ordered α-, γ-, ɛ−Fe2O3 , and Fe3Korovin1, Gastev2, Волков3 et al. 2018Phys. Rev. Materials232230View full textAdd to dashboardCite

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Tunable polymorphism of epitaxial iron oxides in the four-in-one ferroic-on-GaN system with magnetically ordered α-, γ-, ɛ−Fe2O3 , and Fe3
Korovin¹,
Gastev²,
Волков³
et al. 2018
Phys. Rev. Materials
23
2
23
0
View full text Add to dashboard Cite