Fabrication and Magnetoresistance Properties of Spin-Dependent Tunnel Junctions Using an Epitaxial Fe3O4 Film

Matsuda, Hirofumi; Takeuchi, Manabu; Adachi, Hideaki; Hiramoto, Makoto; Matsukawa, Nozomu; Odagawa, Akihiro; Setsune, Kentaro; Sakakima, H.

doi:10.1143/jjap.41.l387

Cited by 41 publications

(15 citation statements)

References 14 publications

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“…This makes magnetite a prospective material for spintronic devices. [9][10][11] Fe 3 O 4 crystallizes in the cubic inverse spinel structure ͑space group Fd3m, a = 8.396 Å͒ where the oxygen anions ͑O 2− ͒ form a close-packed face-centered-cubic ͑fcc͒ sublattice with Fe 2+ and Fe 3+ cations located in interstitial sites. 1 Two different kinds of cation sites exist in the magnetite crystal: tetrahedrally coordinated A sites occupied by Fe A ͑typically assigned with a charge state 3+͒, and octahedrally coordinated B sites occupied by Fe B ͑typically assigned with charge states 2+ and 3+ in equal numbers͒.…”

Section: Introductionmentioning

confidence: 99%

Surface electronic structure of theFe3O4(100): Evidence of a half-metal to metal transition

et al. 2005

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In situ prepared Fe 3 O 4 ͑100͒ thin films were studied by means of scanning tunneling microscopy ͑STM͒ and spin-polarized photoelectron spectroscopy ͑SP-PES͒. The atomically resolved ͑ ͱ 2 ϫ ͱ 2͒R45°wavelike surface atomic structure observed by STM is explained based on density functional theory ͑DFT͒ and ab initio atomistic thermodynamics calculations as a laterally distorted surface layer containing octahedral iron and oxygen, referred to as a modified B layer. The work-function value of the Fe 3 O 4 ͑100͒ surface extracted from the cutoff of the photoelectron spectra is in good agreement with that predicted from DFT. On the Fe 3 O 4 ͑100͒ surface both the SP-PES measurements and the DFT results show a strong reduction of the spin polarization at the Fermi level ͑E F ͒ compared to the bulk density of states. The nature of the states in the majority band gap of the Fe 3 O 4 surface layer is analyzed.

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Section: Introductionmentioning

confidence: 99%

Surface electronic structure of theFe3O4(100): Evidence of a half-metal to metal transition

et al. 2005

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“…However, the amplitude of the giant magnetoresistance 15,16 or tunnel magnetoresistance [17][18][19][20][21][22][23][24][25][26] of devices including Fe 3 O 4 measured to date is much lower than expected from the predicted half metallic character of the compound. The origin of this discrepancy is not fully understood yet but part of the explanation is probably to be found in the significant differences between the magnetic properties of Fe 3 O 4 thin films and those of bulk samples.…”

Section: Introductionmentioning

confidence: 99%

Characterization of antiphase boundary network inFe3O4(111)epitaxial thin films: Effect on anomalous magnetic behavior

et al. 2006

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We report on the antiphase boundaries network of Fe 3 O 4 ͑111͒ thin films. 5-to 50-nm-thick samples were epitaxially grown by molecular beam epitaxy onto ␣-Al 2 O 3 ͑0001͒ substrates. The magnetic properties of the samples have been interpreted within the framework of a one-dimensional model of antiphase boundary ͑APB͒, which predicts that the magnetization is given by M ϱ ͑1−b / ͱ H͒ in the approach to saturation regime. Transmission electron micrographs of several samples were used to extract the statistical parameters of the APB network, particular emphasis being put on the relevance and statistical significance of the studied parameters. The mean antiphase domain size D , as the antiphase boundaries characteristic length l 0 extracted from a fractal analysis, vary as the square root of film thickness/deposition time and are within the 10 nm range. The APB density was found to vary as 1 / l 0 as expected from the fractal dimensions of the network. The dependency of the b parameter of the magnetic model on the APB density is finally analyzed in the light of micromagnetic simulations of chains including finite size antiphase domains and two APBs.

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“…For comparison of film properties, the same meander structure was also patterned on the same substrate adjacent to the biepitaxial grain boundary but not crossing it. However, under the antiparallel magnetization situation with the field between 550 and 700 Oe, there was a substantial increase of MR value at the low field, expected for SDT junction, 5,9,17 was scarcely observed. Figure 7(a) and 7(b) represent the MR curves for the Fe 3 O 4 biepitaxial film at room temperature and 120 K ( just below the Verwey transition temperature), respectively.…”

Section: Magnetoresistance Propertiesmentioning

confidence: 83%

Preparation and characteristics of 90° rotated biepitaxial Fe₃O₄ thin films

et al. 2002

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In-plane 90° rotated biepitaxial Fe3O4 thin films have been successfully prepared onto MgO (110) substrates using a CeO2 seed layer and their microstructure, electric, and magnetic properties were investigated. From the x-ray φ-scan measurements, the in-plane epitaxial relations were determined as 〈110〉Fe3O4//〈110〉MgO and 〈001〉Fe3O4//〈001〉MgO for the no-seeded Fe3O4 layer, and 〈001〉Fe3O4//〈110〉MgO and 〈110〉Fe3O4//〈001〉MgO for the CeO2 (110) seeded Fe3O4 layer. The CeO2 seed layer was found to rotate the upper Fe3O4 lattice at 90° upon normal axis to the layer against the no-seeded Fe3O4. The transmission electron microscopy and electron diffraction analyses revealed that the transition region of the biepitaxial Fe3O4 boundary between CeO2-seeded and no-seeded portions consisted of columnarlike polycrystalline grains. The Fe 3O4 films exhibited single-crystallinelike electric and magnetic properties, however, substantial spin-dependent-tunneling magnetoresistance across the 90° grain boundary was not observed even in the antiparallel situation for each Fe3O4 portion.

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Fabrication and Magnetoresistance Properties of Spin-Dependent Tunnel Junctions Using an Epitaxial Fe3O4 Film

Cited by 41 publications

References 14 publications

Surface electronic structure of theFe3O4(100): Evidence of a half-metal to metal transition

Surface electronic structure of theFe3O4(100): Evidence of a half-metal to metal transition

Characterization of antiphase boundary network inFe3O4(111)epitaxial thin films: Effect on anomalous magnetic behavior

Preparation and characteristics of 90° rotated biepitaxial Fe₃O₄ thin films

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Fabrication and Magnetoresistance Properties of Spin-Dependent Tunnel Junctions Using an Epitaxial Fe3O4 Film

Cited by 41 publications

References 14 publications

Surface electronic structure of theFe3O4(100): Evidence of a half-metal to metal transition

Surface electronic structure of theFe3O4(100): Evidence of a half-metal to metal transition

Characterization of antiphase boundary network inFe3O4(111)epitaxial thin films: Effect on anomalous magnetic behavior

Preparation and characteristics of 90° rotated biepitaxial Fe3O4 thin films

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Preparation and characteristics of 90° rotated biepitaxial Fe₃O₄ thin films