Evolution of magnetic properties in the vicinity of the Verwey transition in 
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 thin films

Liu, X. H.; Liu, W.; Zhang, Z. D.

doi:10.1103/physrevb.96.094405

Cited by 23 publications

(15 citation statements)

References 76 publications

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“…However, it has been demonstrated that the electronic and magnetic properties of magnetite films can be modified using SrTiO 3 substrates [34,35,36], despite the large lattice mismatch of −7.5%. One advantage of using SrTiO 3 substrates is the possibility of doping and, thus, a tunable conductivity providing either an insulating or metallic substrate which can be used as a bottom electrode in capacitor-like structures [17].…”

Section: Introductionmentioning

confidence: 99%

“…In the case of Fe 3 O 4 /NiO bilayers on both substrates, there are a number of works on electronic structure, interfacial coupling, and magnetic characterization [41,42,43,44], whereas to the best of our knowledge there are no detailed structural studies for these bilayers on SrTiO 3 . However, the magnetic and transport characteristics of such films are sensitive to structural variations, number of defects, or stoichiometric deviations, and can be affected by the strain between film and substrate [36]. Therefore, in this work, a comprehensive structural characterization of Fe 3 O 4 /NiO bilayers of different thicknesses grown on Nb-doped SrTiO 3 (001) and for comparison on MgO(001) is presented.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Strain and Morphology on Magnetic Properties of Fe3O4/NiO Bilayers Grown on Nb:SrTiO3(001) and MgO(001)

et al. 2018

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We present a comparative study of the morphology and structural as well as magnetic properties of crystalline Fe3O4/NiO bilayers grown on both MgO(001) and SrTiO3(001) substrates by reactive molecular beam epitaxy. These structures were investigated by means of X-ray photoelectron spectroscopy, low-energy electron diffraction, X-ray reflectivity and diffraction, as well as vibrating sample magnetometry. While the lattice mismatch of NiO grown on MgO(001) was only 0.8%, it was exposed to a lateral lattice mismatch of −6.9% if grown on SrTiO3. In the case of Fe3O4, the misfit strain on MgO(001) and SrTiO3(001) amounted to 0.3% and −7.5%, respectively. To clarify the relaxation process of the bilayer system, the film thicknesses of the magnetite and nickel oxide films were varied between 5 and 20 nm. While NiO films were well ordered on both substrates, Fe3O4 films grown on NiO/SrTiO3 exhibited a higher surface roughness as well as lower structural ordering compared to films grown on NiO/MgO. Further, NiO films grew pseudomorphic in the investigated thickness range on MgO substrates without any indication of relaxation, whereas on SrTiO3 the NiO films showed strong strain relaxation. Fe3O4 films also exhibited strong relaxation, even for films of 5 nm thickness on both NiO/MgO and NiO/SrTiO3. The magnetite layers on both substrates showed a fourfold magnetic in-plane anisotropy with magnetic easy axes pointing in 100 directions. The coercive field was strongly enhanced for magnetite grown on NiO/SrTiO3 due to the higher density of structural defects, compared to magnetite grown on NiO/MgO.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of Strain and Morphology on Magnetic Properties of Fe3O4/NiO Bilayers Grown on Nb:SrTiO3(001) and MgO(001)

et al. 2018

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“…8 In epitaxial Fe 3 O 4 films grown on MgO, Al 2 O 3 , and SrTiO 3 substrates, the mis-stacking of the Fe 3 O 4 lattice on a substrate at the first stage of nucleation could form antiphase boundaries (APBs) which preserve the electronic and magnetic properties of Fe 3 O 4 films away from its bulk one. [9][10][11][12][13][14][15] Across APBs, magnetic moments are coupled antiferromagnetically. 16,17 The spin interaction under the magnetic field across APB is considered to illustrate the MR in Fe 3 O 4 .…”

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confidence: 99%

Magnetoresistance of epitaxial and polycrystalline Fe3O4 films near Verwey transition

Liu

Zhang

et al. 2018

Applied Physics Letters

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We report investigations of magnetoresistance (MR) in epitaxial and polycrystalline Fe 3 O 4 films. MR in epitaxial Fe 3 O 4 films exhibits a local maximum at T V and a large value of À20% at 60 K. Based on a 1D half infinite spin chain model, the fitting parameter, which depends on the volume fraction of electronic scattering boundaries, sharply increases below T V with the decreased temperature. We suppose that the twin boundaries formed below T V facilitate the increase in MR and can act as antiphase boundaries (APBs) where the magnetic moments across twin boundaries are coupled antiferromagnetically. Similar MR behavior in Fe 3 O 4 (100) and (111) epitaxial films manifests the independence of MR on the spatial distribution of APBs. The outline of normalized MR in the epitaxial films shows a distinct temperature dependence. The temperature dependence may result from the different electronic transport mechanisms in Fe 3 O 4 films. In a polycrystalline Fe 3 O 4 film, MR comes from the disordered distribution of magnetic moments at grain boundaries. The effects of APBs, twin boundaries, and grain boundaries on MR are discussed in detail.

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“…1998; Liu et al. 2017) and the remanence held by magnetite after cooling through (Özdemir and Dunlop 1999; Özdemir 2000; Heider et al. 1992; King and Williams 2000).…”

Section: Introductionmentioning

confidence: 99%

The effects of dislocations on crystallographic twins and domain wall motion in magnetite at the Verwey transition

Lindquist

Feinberg

Harrison

et al. 2019

Earth Planets Space

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Pure magnetite experiences a first-order phase transition (the Verwey transition) near 120–125 K wherein the mineral’s symmetry changes from cubic to monoclinic. This transformation results in the formation of fine-scale crystallographic twins and is accompanied by a profound change in magnetic properties. The Verwey transition is critical to a variety of applications in environmental magnetism and paleomagnetism because its expression is diagnostic for the presence of stoichiometric (or nearly stoichiometric) magnetite and cycling through the Verwey transition tends to remove the majority of multidomain magnetic remanence. Internal and external stresses demonstrably affect the onset of the Verwey transition. Dislocations create localized internal stress fields and have been cited as a possible source of an altered Verwey transition in deformed samples. To further investigate this behavior, a laboratory-deformed magnetite sample was examined inside a transmission electron microscope as it was cooled through the Verwey transition. Operating the microscope in the Fresnel mode of Lorentz microscopy enabled imaging of the interactions between dislocations, magnetic domain walls, and low-temperature crystallographic twin formation during the phase transition. To relate the observed changes to more readily measurable bulk sample magnetic behavior, low-temperature magnetic measurements were also taken using SQUID magnetometry. This study allows us, for the first time, to observe the Verwey transition in a defect-rich area. Dislocations, and their associated stress fields, impede the development of monoclinic magnetite twin structures during the phase transition and increase the remanence of a magnetite sample after cooling and warming through the Verwey transition. Electronic supplementary material The online version of this article (10.1186/s40623-018-0981-7) contains supplementary material, which is available to authorized users.

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Evolution of magnetic properties in the vicinity of the Verwey transition in Fe3O4 thin films

Cited by 23 publications

References 76 publications

Impact of Strain and Morphology on Magnetic Properties of Fe3O4/NiO Bilayers Grown on Nb:SrTiO3(001) and MgO(001)

Impact of Strain and Morphology on Magnetic Properties of Fe3O4/NiO Bilayers Grown on Nb:SrTiO3(001) and MgO(001)

Magnetoresistance of epitaxial and polycrystalline Fe3O4 films near Verwey transition

The effects of dislocations on crystallographic twins and domain wall motion in magnetite at the Verwey transition

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