Atomic-scale analysis of CoFe/Cu and CoFe/NiFe interfaces

Larson, D.J.; Clifton, P. H.; Tabat, N.; Cerezo, A.; Petford-Long, A. K.; Martens, R. L.; Kelly, Tom

doi:10.1063/1.127099

Cited by 55 publications

(35 citation statements)

References 15 publications

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“…The samples were sharpened into the needleshaped geometry required for the atom probe using focused ion beam milling. 9,10,12 The analyses were performed in an energy-compensated optical position-sensitive atom probe in a vacuum of ¾5 ð 10 9 Pa and specimens were cooled to temperatures close to 70 K. Analyses were performed along the tip axis, which is also the <111> direction of the specimens. The ion probe images are extracted from larger three-dimensional images reconstructed from raw data in two different layer orientations: perpendicular to the tip axis and slightly tilted from this direction (the rotation angle between the layer and the <111> direction is equal to 5°).…”

Section: Methodsmentioning

confidence: 99%

“…Recent experimental results have been obtained by Larson et al on materials composed of repeats of Co 90 Fe 10 layers separated by Cu layers. 9,10 Multilayer thin films fabricated using Co and Cu have been widely studied because they exhibit not only good giant magnetic resistance performance but are also relatively stable at high temperatures. 11 However, the magnetic and transport properties of these materials are strongly dependent on the microstructure and the composition variations across these layers at the atomic scale.…”

Section: Introductionmentioning

confidence: 99%

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Improvement of multilayer analyses with a three‐dimensional atom probe

Vurpillot¹,

Larson²,

Cerezo³

2004

Surface & Interface Analysis

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Owing to their giant magnetoresistance properties, multilayer thin-film materials are widely used in information storage technology. However, because this magnetic behaviour is highly sensitive to interface roughness and diffusivity on a subnanometre scale, the structural characterization of these materials with high spatial resolution is of fundamental importance. The three-dimensional atom probe is one of the instruments that theoretically can provide chemical analyses in three dimensions with the highest spatial resolution. However, because three-dimensional reconstructions can be subject to strong artefacts due to trajectory aberrations, it is important to combine experimental analyses with theoretical investigations of the evaporation and reconstruction process in order to obtain the most accurate data on interface structure.In this paper, a simulation model is used in order to compute the ion trajectories close to a field emitter. The model is modified to take into account the unique morphology of the multilayer thin-film structure. This model gives a sound interpretation of the three-dimensional atom probe images of multilayer thin films. The three-dimensional atom probe reconstructions of NiFe/FeCo/Cu multilayer structures are found to be degraded by strong artefacts owing to the difference in evaporation field between the FeCo layer and the Cu layer. By using simulation, these aberration effects are interpreted as errors in the calculation of the z-dimension within three-dimensional images. A correction procedure has been developed to improve the reconstruction of multilayer thin films in the three-dimensional atom probe.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improvement of multilayer analyses with a three‐dimensional atom probe

Vurpillot¹,

Larson²,

Cerezo³

2004

Surface & Interface Analysis

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“…The specimen was made by FIB sharpening of Si posts as in the work on multilayers above ͑see Ref. 136 for example͒. This silicon work was not published except as a note in a conference proceedings.…”

Section: Silicon-based Structuresmentioning

confidence: 99%

Atom probe tomography

Kelly¹,

Miller

2007

Review of Scientific Instruments

752

345

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The technique of atom probe tomography ͑APT͒ is reviewed with an emphasis on illustrating what is possible with the technique both now and in the future. APT delivers the highest spatial resolution ͑sub-0.3-nm͒ three-dimensional compositional information of any microscopy technique. Recently, APT has changed dramatically with new hardware configurations that greatly simplify the technique and improve the rate of data acquisition. In addition, new methods have been developed to fabricate suitable specimens from new classes of materials. Applications of APT have expanded from structural metals and alloys to thin multilayer films on planar substrates, dielectric films, semiconducting structures and devices, and ceramic materials. This trend toward a broader range of materials and applications is likely to continue.

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“…One can deposit the multilayers on a planar substrate and then sharpen tip-shaped specimens of the required radius by means of focused ion beam milling. 8,9 An alternative possibility is to prepare needle-shaped substrates by means of electropolishing and to deposit multilayers subsequently. 10 -12 For the present paper the specimens were prepared using the latter technique because of its higher throughput.…”

Section: Methodsmentioning

confidence: 99%

Thermal reaction and stability of NiFe/Cu thin films investigated by atom probe tomography

Ene¹,

Schmitz

Kirchheim³

et al. 2007

Surface & Interface Analysis

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NiFe/Cu multilayer stacks of 2 nm single layer thickness were deposited onto needle-shaped W tips by ion beam sputtering and analysed by atom probe tomography (TAP) after appropriate heat treatments. After annealing at 250°C for 30 min, no significant structural or chemical transformation of the initial layer system is detected, although such a heat treatment appreciably reduces the magneto resistivity. A slight decrease of the concentration slope at the interfaces is attributed to a very short-range interdiffusion. Clear grain boundary diffusion is observed after annealing at 400°C for 30 min. Further annealing at 500°C for 20 min and 40 min still preserves the layered structure with a homogeneous solution of Ni inside the Cu layers of up to 25 at.% Ni.

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Atomic-scale analysis of CoFe/Cu and CoFe/NiFe interfaces

Abstract: Atom probe analysis of roughness and chemical intermixing in CoFe/Cu films (invited)Role of the buffer layers in determining the antiferromagnetic coupling and magnetoresistance of NiFeCo/Cu superlattices J.

Cited by 55 publications

References 15 publications

Improvement of multilayer analyses with a three‐dimensional atom probe

Improvement of multilayer analyses with a three‐dimensional atom probe

Atom probe tomography

Thermal reaction and stability of NiFe/Cu thin films investigated by atom probe tomography

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