Thin Al, Au, Cu, Ni, Fe, and Ta films as oxidation barriers for Co in air

Gan, L; Gomez, R. D.; Powell, Cedric J.; McMichael, Robert D.; Chen, P. J.; Egelhoff, William F.

doi:10.1063/1.1543873

Cited by 28 publications

(14 citation statements)

References 7 publications

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“…Both AES and the absence of oxidation of the Co on exposure to atmosphere confirm that the Co does not segregate to the surface. The RAS-MOKE spectra measured immediately after growth have remained unchanged over a period of months indicating that the sample has remained protected by the capping layer [16]. In addition, capped 2-, 3-and 4-atom wide wires show oscillatory behaviour in their coercivity, similar to that observed for uncapped wires [17].…”

Section: Resultsmentioning

confidence: 51%

X‐ray magnetic circular dichroism and reflection anisotropy spectroscopy Kerr effect studies of capped magnetic nanowires

Cunniffe

McNally

Liberati

et al. 2010

Physica Status Solidi (b)

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Aligned Co wires grown on Pt(997) under ultra-high vacuum conditions have been capped successfully by the epitaxial growth of Au monolayers (ML) at room temperature. The samples were kept under vacuum except when transferring between apparatus or when making some of the measurements. No degradation of the Co wires was detected during the measurements. The magneto-optic response of the system was measured using xray magnetic circular dichroism (XMCD) at the Co L 2,3 edge and reflection anisotropy spectroscopy (RAS) at near-normal-incidence, which is sensitive to the normal component of the out-of-plane magnetization via the Kerr effect (MOKE). Capping the wires significantly impacts their magnetic properties. Comparison of the magnetooptic response of the system at x-ray and optical energies reveals small differences that are attributed to the induced moment in the Pt substrate and Au capping layer not picked up by the element specific XMCD measurements.. The sensitivity of RAS-MOKE is sufficient to allow the determination of the easy axis direction of the capped wires to within a few degrees. The results for a 6-atom-wide Co wire sample, capped with 6 ML of Au, are consistent with the capped wires possessing perpendicular magnetization.

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Section: Resultsmentioning

confidence: 51%

X‐ray magnetic circular dichroism and reflection anisotropy spectroscopy Kerr effect studies of capped magnetic nanowires

Cunniffe

McNally

Liberati

et al. 2010

Physica Status Solidi (b)

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“…The mean cluster size deposited was n = 15, 600, 2300 and 6500atoms/cluster, all distributions showing ratios between σ/ n ≈ 0.6 − 0.16 for the smallest and largest cluster distributions used, respectively. The samples were capped by Cu films of 4nm thickness, enough to ensure oxidization protection after exposure to air [22].…”

Section: Resultsmentioning

confidence: 99%

Monodispersed metal clusters in solid matrices: A new experimental setup

Hillenkamp

Domenicantonio

Félix

2006

Review of Scientific Instruments

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We describe a new experimental setup for the production of samples of metal clusters embedded in matrices stable at ambient conditions. The cluster ions are generated in the gas phase and codeposited fragmentation-free together with the evaporated matrix. Mean cluster sizes range from a few to many thousands of atoms. For small clusters (n < 20) mass selection is possible, larger clusters are deposited in narrow size distributions. Matrix materials include metals (Cu, Ag) and oxides such as quartz. The performance of the apparatus as well as sample characterization procedures are described. We show first results on the magnetic properties of different cobalt cluster size distributions ( n = 15, 600, 2300, 6500) embedded in copper matrices, demonstrating inter-cluster as well as cluster-lattice interactions.

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“…26,27 Thin capping layers (Շ10 nm) were also used to allow direct XPS verification of barrier integrity and check for cap-layer/sample-surface reactions. 28 Here, we investigate the effectiveness of metal capping layers for nondestructive high-resolution XPS analyses of ceramic thin films. We use, as a model materials system, polycrystalline 200-nm-thick NaCl-crystal structure TiN layers grown on Si(001) substrates at 400 C by reactive magnetron sputter deposition in mixed N 2 /Ar atmospheres.…”

Section: Introductionmentioning

confidence: 99%

Al capping layers for nondestructive x-ray photoelectron spectroscopy analyses of transition-metal nitride thin films

Greczyński¹,

Petrov²,

Greene³

et al. 2015

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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X-ray photoelectron spectroscopy (XPS) compositional analyses of materials that have been air exposed typically require ion etching in order to remove contaminated surface layers. However, the etching step can lead to changes in sample surface and near-surface compositions due to preferential elemental sputter ejection and forward recoil implantation; this is a particular problem for metal/gas compounds and alloys such as nitrides and oxides. Here, the authors use TiN as a model system and compare XPS analysis results from three sets of polycrystalline TiN/Si(001) films deposited by reactive magnetron sputtering in a separate vacuum chamber. The films are either (1) air-exposed for ≤10 min prior to insertion into the ultrahigh-vacuum (UHV) XPS system; (2) air-exposed and subject to ion etching, using different ion energies and beam incidence angles, in the XPS chamber prior to analysis; or (3) Al-capped in-situ in the deposition system prior to air-exposure and loading into the XPS instrument. The authors show that thin, 1.5–6.0 nm, Al capping layers provide effective barriers to oxidation and contamination of TiN surfaces, thus allowing nondestructive acquisition of high-resolution core-level spectra representative of clean samples, and, hence, correct bonding assignments. The Ti 2p and N 1s satellite features, which are sensitive to ion bombardment, exhibit high intensities comparable to those obtained from single-crystal TiN/MgO(001) films grown and analyzed in-situ in a UHV XPS system and there is no indication of Al/TiN interfacial reactions. XPS-determined N/Ti concentrations acquired from Al/TiN samples agree very well with Rutherford backscattering and elastic recoil analysis results while ion-etched air-exposed samples exhibit strong N loss due to preferential resputtering. The intensities and shapes of the Ti 2p and N 1s core level signals from Al/TiN/Si(001) samples do not change following long-term (up to 70 days) exposure to ambient conditions, indicating that the thin Al capping layers provide stable surface passivation without spallation.

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Thin Al, Au, Cu, Ni, Fe, and Ta films as oxidation barriers for Co in air

Cited by 28 publications

References 7 publications

X‐ray magnetic circular dichroism and reflection anisotropy spectroscopy Kerr effect studies of capped magnetic nanowires

X‐ray magnetic circular dichroism and reflection anisotropy spectroscopy Kerr effect studies of capped magnetic nanowires

Monodispersed metal clusters in solid matrices: A new experimental setup

Al capping layers for nondestructive x-ray photoelectron spectroscopy analyses of transition-metal nitride thin films

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