Quantitative study of the interdependence OF interface structure and giant magnetoresistance in polycrystalline Fe/Cr superlattices

Schad, R.; Beliën, P.; Verbanck, G.; Potter, C. D.; Fischer, Henry E.; Lefébvre, S.; Bessière, M.; Moshchalkov, Victor; Bruynseraede, Y.

doi:10.1103/physrevb.57.13692

Cited by 37 publications

(21 citation statements)

References 37 publications

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“…71 A reduction of GMR was found with increasing the amplitude of the interface roughness having a constant correlation length, as is shown in Fig.14b. This fact demonstrates that spin-dependent scattering is very sensitive to the details of the microstructure of the interfaces.…”

Section: Roughness Dependencementioning

confidence: 53%

Perspectives of giant magnetoresistance

Tsymbal¹,

Pettifor²

2001

Solid State Physics

252

189

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Section: Roughness Dependencementioning

confidence: 53%

Perspectives of giant magnetoresistance

Tsymbal¹,

Pettifor²

2001

Solid State Physics

252

189

View full text Add to dashboard Cite

“…9,18 Thus experiments that relate directly the physical and magnetic structure of FM1/OSC/FM2 systems with the existence or non-existence of large MR effects in such structures are essential. In particular, X-ray reflectometry (XRR) 19,20 and polarized neutron reflectometry (PNR), 21 with their ability to probe the structural and magnetic properties of buried interfaces, are well suited to this task. Here we report XRR and PNR results, in conjunction with SQUID magnetometery, Auger depth profiling, and electrical transport studies to correlate the microstructure and magnetotransport in OSC spin valve structures.…”

Section: 1213mentioning

confidence: 99%

Correlation between microstructure and magnetotransport in organic semiconductor spin-valve structures

et al. 2009

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We have studied magnetotransport in organic-inorganic hybrid multilayer junctions. In these devices, the organic semiconductor (OSC) Alq 3 (tris(8-hydroxyquinoline) aluminum) formed a spacer layer between ferromagnetic (FM) Co and Fe layers. The thickness of the Alq 3 layer was in the range of 50-150 nm. Positive magnetoresistance (MR) was observed at 4.2 K in a current perpendicular to plane geometry, and these effects persisted up to room temperature. The devices' microstructure was studied by X-ray reflectometry, Auger electron spectroscopy and polarized neutron reflectometry (PNR). The films show well-defined layers with modest average chemical roughness (3-5 nm) at the interface between the Alq 3 and the surrounding FM layers. Reflectometry shows that larger MR effects are associated with smaller FM/Alq 3 interface width (both chemical and magnetic) and a magnetically dead layer at the Alq 3 /Fe interface. The PNR data also show that the Co layer, which was deposited on top of the Alq 3 , adopts a multi-domain magnetic structure at low field and a perfect anti-parallel state is not obtained. The origins of the observed MR are discussed and attributed to spin coherent transport. A lower bound for the spin diffusion length in Alq 3 was estimated as 43 ± 5 nm at 80 K. However, the subtle correlations between microstructure and magnetotransport indicate the importance of interfacial effects in these systems.

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“…. Hard x-rays in the 5-10 keV can be reflected from buried interfaces and planar multilayer nanostructures so as to set up standing waves that may permit depth-dependent composition, structure, and, via variable light polarization or magnetization direction, also magnetism near buried interfaces to be derived 6,7 . But these hard x-ray measurements are limited as to both energy resolution and spectroscopic characterization, and also may due to their shorter wavelengths (∼1-2 Å) exhibit interference structures from atomic lattice planes that can be much smaller than the nanometer scale it is desired to probe.…”

mentioning

confidence: 99%

Probing buried interfaces with soft x-ray standing wave spectroscopy: application to the Fe/Cr interface

Yang

Mun

Mannella

et al. 2002

J. Phys.: Condens. Matter

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Many current technological devices consist of layered or sandwich structures, the thickness of whose composite layers is either already in the nanometer (10 Å) range or in the process of shrinking into the nanometer range. These devices include transistors in integrated circuits, solid-state lasers, and magnetic elements for storing information and for reading it out. Such interfaces may exhibit intermixing of the components on either side and/or roughness, as well as altered chemical states or states of magnetic order, and their exact nature can affect ultimate properties such as electrical conductivity or magnetic stability in a profound way. As one example of such nanostructures in magnetism, the phenomenon of giant magnetoresistance (GMR) is based on the change in resistance in a sandwich structure consisting of alternating non-magnetic and magnetic layers upon being exposed to an external magnetic field 1,2 . GMR is today used routinely in the read heads for highest density information storage, where it is usually combined with another interface-driven effect, exchange Some of these questions can be answered at least partially using currently available methods, and we briefly mention a few of these. One powerful method is scanning transmission electron 2 microscopy (STEM) with electron energy loss spectroscopy (EELS) 5 , but this technique requires specialized sample slicing and thinning and thus cannot be considered non-destructive, and in its most sophisticated element-specific form with EELS still cannot provide both element specificity and magnetic sensitivity at the sub-nanometer scale. . Hard x-rays in the 5-10 keV can be reflected from buried interfaces and planar multilayer nanostructures so as to set up standing waves that may permit depth-dependent composition, structure, and, via variable light polarization or magnetization direction, also magnetism near buried interfaces to be derived 6,7 . But these hard x-ray measurements are limited as to both energy resolution and spectroscopic characterization, and also may due to their shorter wavelengths (∼1-2 Å) exhibit interference structures from atomic lattice planes that can be much smaller than the nanometer scale it is desired to probe. Another method uses total reflection of soft xrays in the 0.5-1.5 keV range from a buried interface by tuning the photon energy to a core-level absorption edge 8 , and this can determine both chemical and magnetic roughness by working with both right and left circularly polarized radiation (RCP and LCP, respectively) and/or flipping the sample magnetization between two orientations 1 and 2 and measuring a magnetic asymmetry in diffuseHowever, this method does not permit detailed spectroscopic studies (e.g. via photoelectron emission) of the buried interface. Finally, soft x-ray spectromicroscopy using secondary electrons as the detecting medium can achieve some sensitivity to buried interfaces, provided that there are sufficient chemical fingerprints in the x-ray absorption signal to deconvolve the interface contrib...

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Quantitative study of the interdependence OF interface structure and giant magnetoresistance in polycrystalline Fe/Cr superlattices

Cited by 37 publications

References 37 publications

Perspectives of giant magnetoresistance

Perspectives of giant magnetoresistance

Correlation between microstructure and magnetotransport in organic semiconductor spin-valve structures

Probing buried interfaces with soft x-ray standing wave spectroscopy: application to the Fe/Cr interface

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