Epitaxial Pt(001), Pt(110), and Pt(111) films on MgO(001), MgO(110), MgO(111), and Al2O3(0001)

Lairson, B. M.; Visokay, M.R.; Sinclair, Robert; Hagström, S. B. M.; Clemens, Bruce M.

doi:10.1063/1.107547

Cited by 125 publications

(50 citation statements)

References 7 publications

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“…In our experiment Al 2 O 3 (0001) oriented substrates were used to promote formation of Pt fcc (111) buffer layer structure [18][19][20][21][22] and further (111) orientation of successive Fe/Pt bilayers. (0001) Al 2 O 3 surface morphology is well known to strongly depend on preparation procedure e.g.…”

Section: Substrate Preparation and Sample Growthmentioning

confidence: 99%

Structural and Magnetic Properties of MBE Grown (Fe/Pt) (111) Multilayers

et al. 2016

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Series of Al2O3(0001)/Pt/(Fe/Pt)n/Pt multilayers with variable number of bilayers n and thicknesses of individual layers were grown using molecular beam epitaxy to investigate influence of buffer layer structure, number of bilayers, and individual layer thickness on their structural and magnetic properties. Both columnar and monocrystalline 10 nm Pt (111) buffer layers were used in the experiment. Structure of Pt buffer layer determined the roughness of Fe/Pt interfaces and consequently magnetic properties of the multilayers. When multilayers were deposited on columnar Pt buffer layer, we observed increase of Fe/Pt interfaces roughness with increasing number of bilayers to values exceeding the nominal Fe/Pt bilayer thickness in the upper part of the sample volume, which resulted in the increment of coercivity in the sample with n = 15 determined from hysteresis loops measured for perpendicular orientation of magnetic field. When Fe/Pt multilayers were deposited on monocrystalline Pt buffer layer, Fe/Pt interfaces were smooth regardless the number of bilayers. All samples, despite of the quality of buffer layer, number of bilayers, and individual layer thickness revealed easy magnetisation axis oriented in the sample plane.

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Section: Substrate Preparation and Sample Growthmentioning

confidence: 99%

Structural and Magnetic Properties of MBE Grown (Fe/Pt) (111) Multilayers

et al. 2016

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“…Due to the potentially disturbing ferromagnetic properties of FePt, we decided to use pure Pt as a seed layer for Cu growth, exhibiting a temperature dependent change in crystal structure from a (111) regime at ambient deposition temperatures to a (100)-oriented regime parallel to the substrate lattice in a temperature range above 950 K [33].…”

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confidence: 99%

“…The substrates were carefully cleaned in multiple cycles by organic solvents (acetone, isopropanol) and subsequently heated in the sputtering chamber at 970 K for 2 h to remove contaminations. To achieve the crystalline properties mentioned in [33], appropriate temperatures were applied during layer deposition. For the (111)-oriented Pt buffer (LTPt), a temperature of 650 K was chosen, while the (100)-oriented Pt (HTPt) was deposited at a temperature of 950 K to exclude any formation of (111) domains.…”

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confidence: 99%

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Preparation and characterisation of epitaxial Pt/Cu/FeMn/Co thin films on (100)‐oriented MgO single crystals

Schmidt

Gräfe

Audehm

et al. 2015

Physica Status Solidi (a)

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This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.FeMn/Co thin-films, a purely metallic exchange-bias system, were prepared on (100)-oriented MgO single crystals. The layers were grown by molecular beam epitaxy (MBE). The crystalline and magnetic properties could be tuned by using sputtered Pt buffer layers deposited at variable temperatures. A transition of the crystalline orientation from (111)-terminated layers at lower deposition temperatures to (100)-terminated layers at temperatures higher than 950 K was established and the impact on the magnetic sample properties was investigated. Here, the detailed sample preparation process is shown together with low energy electron diffraction (LEED), medium energy electron diffraction (MEED), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements revealing the samples structure and composition. The crystalline orientation of Pt was imprinted to the magnetic layer stack and clearly influenced the exchangebias (EB) and coercive field (H C ) as shown by superconducting quantum interference device (SQUID) and magneto-optical Kerr effect (MOKE) measurements. Furthermore, a correlation between the crystallite size and the temperature dependent magnetic properties could be identified.

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“…[44][45][46] MgO has the standard cubic rock salt crystal structure. MgO(001) substrates were selected for use in the high temperature codeposition experiments described here due to its previously demonstrated ability to grow W and WC epitaxially in magnetron sputtered films.…”

Section: Section 22: Magnesium Oxide (Mgo)mentioning

confidence: 99%

Synthesis and Oxidation of non-Stoichiometric Tungsten Carbide Studied by Scanning Tunneling Microscopy/Spectroscopy

McClimon¹

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Tungsten Carbide (WC) is a promising catalyst material for applications where cost is paramount, such as microbial fuel cells. Unfortunately, oxidation depresses performance which is a critical problem with respect to long term performance. In this work, non-stoichiometric carbon-rich WC is investigated to infer whether an excess of carbon near the surface can reduce or be utilized to repair oxidation of the active catalytic surface. The carbides are synthesized via a physical vapor deposition of metallic tungsten and C 60 , which allows fine control over the composition of the resulting film. The films are studied predominantly via Scanning Tunneling Microscopy/Spectroscopy (STM/STS).Prior to synthesizing the carbide, a number of RT depositions are performed onto graphite substrates to understand the interactions between the C 60 and W prior to thermallyinduced destruction of the C 60 cage and formation of the carbides. These experiments showed a surprising lack of interaction between small W clusters and adjacent C 60 molecules. This result contrasts with literature of analogous experiments showing significant charge transfer from W to C 60 and strong interaction as a result. For W deposited on top of C 60 layers, it is found that isolated W atoms diffuse easily into the interstices of the C 60 matrix and that for high coverages, interactions between the W and C 60 induce a significant reduction in the C 60 bandgap. These interactions can also stabilize very small islands of C 60 on graphite that otherwise require hundreds of molecules before a stationary C 60 island can form.Intermediate annealing at 400-500C of C 60 on epitaxial W/MgO(100) produces novel nanostructures with a very similar size and shape to C 60 but with metallic conductivity, a unique atomic-scale stripe pattern on their surface, occasional mobility under the influence of the STM iv tip, and show signs of evolving towards WO 3 under oxidation. These structures increase in diameter and slowly dissolve into the W surface under increasing annealing temperatures.Carbide thin films are synthesized by codeposition onto MgO substrates held above 600˚C. These thin films are determined to be predominantly metastable, cubic WC 1-x phase. At a C/W ratio of 60/40 and above, carbon is observed to surface segregate and form graphite on the surface of the film. At a ratio of 60/40 the surface is heavily populated with graphene, rather than graphite.Oxidation of the films at elevated temperatures in UHV shows that morphological changes, even at atomic resolution, were absent. STS shows that signs of oxidation overspread the surface immediately but that WO 3 nucleates well-defined islands which grow in size with harsher oxidation conditions. For the graphite covered surfaces, graphite appears to protect the underlying carbide from oxidation, and between 300 and 400˚C, O 2 begins to etch the graphite.The underlying carbide appears to oxidize similarly to films without a graphitized surface.Overall, the WC films oxidize much less rapidly than W cluste...

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Epitaxial Pt(001), Pt(110), and Pt(111) films on MgO(001), MgO(110), MgO(111), and Al2O3(0001)

Cited by 125 publications

References 7 publications

Structural and Magnetic Properties of MBE Grown (Fe/Pt) (111) Multilayers

Structural and Magnetic Properties of MBE Grown (Fe/Pt) (111) Multilayers

Preparation and characterisation of epitaxial Pt/Cu/FeMn/Co thin films on (100)‐oriented MgO single crystals

Synthesis and Oxidation of non-Stoichiometric Tungsten Carbide Studied by Scanning Tunneling Microscopy/Spectroscopy

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