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The development of skyrmionic devices requires a suitable tuning of material parameters to stabilize skyrmions and control their density. It has been demonstrated recently that different skyrmion types can be simultaneously stabilized at room temperature in heterostructures involving ferromagnets, ferrimagnets, and heavy metals, offering a new platform of coding binary information in the type of skyrmion instead of the presence/absence of skyrmions. Here, we tune the energy landscape of the two skyrmion types in such heterostructures by engineering the geometrical and material parameters of the individual layers. We find that a fine adjustment of the ferromagnetic layer thickness, and thus its magnetic anisotropy, allows the trilayer system to support either one of the skyrmion types or the coexistence of both and with varying densities.

Machine learning is changing how we design and interpret experiments in materials science. In this work, we show how unsupervised learning, combined with ab initio random structure searching, improves our understanding of structural metastability in multicomponent alloys. We focus on the case of Al-O-N alloys where the formation of aluminum vacancies in wurtzite AlN upon the incorporation of substitutional oxygen can be seen as a general mechanism of solids where crystal symmetry is reduced to stabilize defects. The ideal AlN wurtzite crystal structure occupation cannot be matched due to the presence of an aliovalent hetero-element into the structure. The traditional interpretation of the c-lattice shrinkage in sputter-deposited Al-O-N films from X-ray diffraction (XRD) experiments suggests the existence of a solubility limit at 8 at % oxygen content. Here, we show that such naive interpretation is misleading. We support XRD data with accurate ab initio modeling and dimensionality reduction on advanced structural descriptors to map structure-property relationships. No signs of a possible solubility limit are found. Instead, the presence of a wide range of non-equilibrium oxygen-rich defective structures emerging at increasing oxygen contents suggests that the formation of grain boundaries is the most plausible mechanism responsible for the lattice shrinkage measured in Al-O-N sputtered films. We further confirm our hypothesis using positron annihilation lifetime spectroscopy.

Contemporary spintronics devices, notably GMR and TMR-sensors with high linear ranges, stand to benefit from large bias fields in excess of 1T that have been observed in exchange-coupled double layers using rare earth-transition metal ferrimagnets as pinning layers. However, before exploiting the strong coupling the reversal process must be understood at the scales of the smallest devices, where it would be effective. Little is known about these processes to-date, owing to the technical difficulty of imaging magnetic structures smaller than 20nm in fields of several Tesla. Here we image the nanoscale magnetic structures of a double layer comprising a polycrystalline Co/Pt-multilayer (Co/Pt) which is strongly exchange-coupled to an amorphous and magnetically-hard ferrimagnetic TbFe alloy layer. High resolution magnetic force microscopy provides snapshots of the magnetic structures along various applied fields between 0 and 7T as the magnetization reversal takes place. In contrast to a magnetization reversa...

Skyrmion imaging and electrical detection via topological Hall (TH) effect are two primary techniques for probing magnetic skyrmions, which hold promise for next-generation magnetic storage. However, these two kinds of complementary techniques have rarely been employed to investigate the same samples. We report the observation of nanoscale skyrmions in SrIrO3/SrRuO3 (SIO/SRO) bilayers in a wide temperature range from 10 to 100 K. The SIO/SRO bilayers exhibit a remarkable TH effect, which is up to 200% larger than the anomalous Hall (AH) effect at 5 K, and zero-field TH effect at 90 K. Using variable-temperature, high-field magnetic force microscopy (MFM), we imaged skyrmions as small as 10 nm, which emerge in the same field ranges as the TH effect. These results reveal a rich space for skyrmion exploration and tunability in oxide heterostructures.

Aluminum oxynitride (Al-O-N) is a material suitable for hard, transparent thin films. Its physical properties and structure can be adjusted through the O-to-N ratio. Reactive Direct Current Magnetron Sputtering (R-DCMS) is a practical, widespread technique for the deposition of coatings. However, it proves to be challenging in the case of Al-O-N. The reason for this is the high reactivity of O2. Poisoning of Al targets by O2 causes formation of insulating oxide islands and consequently leads to target destruction and a failure of the deposition process. Here, we show that with two separate gas inlets for the two reactive gases, a good process stability can be achieved over the entire range of O-to-N ratios.

Machine learning is changing how we design and interpret experiments in materials science. In this work, we show how unsupervised learning, combined with

This chapter is related to the field of magnetic force microcopy (MFM), where the probing tip is covered with a magnetic layer and the magnetic domain structure of the sample can be characterized with high lateral resolution. In addition, other scanning probe methods mapping the magnetic field at a microscopic scale and techniques providing access to atomic scale magnetism are reviewed.

This chapter reviews scanning probe microscopy methods that measure the field above a sample contain chiral spin textures. Among those microscopy methods are magnetic force microscopy (MFM), nitrogen vacancy (NV) center microscopy, scanning Hall probe microscopy, and scanning SQUID microscopy. However, only the first two techniques have been applied for the study of chiral spin textures. They can obtain a lateral resolution down to about 10 nm and are sufficiently sensitive to map the stray field from ferromagnetic layer with a thicknesses down to a few atoms. Even submonolayer of spins can be imaged. The information on the magnetic moment distribution inside the sample that can be obtained from the stray field however remains limited because different magnetic moment configurations can generate the same stray field. Thus in most cases the field of candidate magnetization structures is fitted to experimental results. An important advantage of methods imaging the stray field is that these can be applied to sample where the magnetic layer is inside the sample, i.e., below a layer protecting it against oxidation. This makes these experimental methods suitable for the reliable imaging of technologically relevant samples.

Magnetic properties of [Co(0.4 nm)/Pt(0.7 nm)]5 multilayers are tailored by controlling the sputtering voltage during the growth of cobalt layers by a facing target cathode. It is shown that increasing sputtering voltage up to 150 V leads to an improved crystalline texture and this results in larger magnetic anisotropies and out-of-plane coercive fields. At a higher cathode voltage of 540 V however crystalline texture quality slightly worsens and this is accompanied by a decrease in the effective anisotropy. Using facing target cathode sputtering, the crystalline structure of the multilayers can be controlled without applying any heat treatment and this can be used to optimize the magnetic properties of Co/Pt multilayers for specific applications.

Future prospects of scanning probe microscopy are discussed. Arrays of cantilevers can be used for ultrasensitive bio-sensors or be used as a mechanical storage medium. The role of scanning probe microscopy in fields of nanoscience, nanotechnology but also quantum information will be elaborated.

In this chapter, some other members of the scanning probe microscopy family are briefly described. All probe microscopes are based upon probing tips, but some tips are rather different from standard STM tips. Methods such as scanning near-field optical microscopy (SNOM), scanning ion conductance microscopy (SICM) or photoemission microscopy with scanning aperture (PEMSA), are based on tips with apertures, where light, ions or electrons can pass through. The scanning near-field acoustic microscope (SNAM) is the acoustic analogue of the SNOM. Other methods essentially depend on a standard STM feedback and measure outcoming radiation, as in the case of STM with inverse photoemission (STMiP), or measure the influence of incoming light on the tunneling current, as in the case of laser STM (LSTM), or measure the temperature of the tip, as in the case of scanning thermal microscopy (SThM), or perform measurements in an electrolyte, as in the case of electrochemical STM (ECSTM). In scanning noise microscopy (SNM), the noise of the tunneling current is measured at a compensated thermovoltage. In scanning capacitance microscopy (SCM), the capacitance between probing tip and sample is measured. In scanning potentiometry microscopy (SPotM), the electrical potential, which depends on the resistivity of the sample, is measured. In scanning spreading resistance microscopy (SSRM), the spreading resistance is monitored. Finally, scanning tunneling atom probe (STAP) is an example of the combination of STM with a time-of-flight mass spectrometer, where the mass of single ions from the probing tip can be analyzed.

This chapter reviews the principles and contrast mechanisms of the spin-polarized scanning tunneling microscope (SP-STM) and magnetic exchange force microscope (MExFM) and the application of these instruments to explore spin spirals and skyrmions in materials with Dzyaloshinkii-Moriya interaction.

The current-driven motion of skyrmions in MnSi and FeGe thinned single crystals could be initiated at current densities of the order of 106 A/m2, five orders of magnitude smaller than for magnetic domain walls. The technologically crucial step of replicating these results in thin films has not been successful to-date, but the reasons are not clear. Elucidating them requires analyzing system characteristics at scales of few nm where the key Dzyaloshinskii-Moriya (DM) interactions vary, and doing so in near-application conditions, i.e. in systems at room temperature, capped with additional layers for oxidation protection. In this work’s magnetic force microscopy (MFM) studies of magnetron-sputtered Ir/Co/Pt-multilayers we show skyrmions that are smaller than previously observed, are not circularly symmetric, and are pinned to 50-nm wide areas where the DM interaction is higher than average. This finding matches our measurement of inhomogeneity of the magnetic moment areal density, which amounts to a standard deviation of the Co layer thickness of 0.3 monolayers in our 0.6 nm thick Co layers. This likely originates in small Co layer thickness variation and alloying. These film characteristics must be controlled with greater precision to preclude skyrmion pinning.

An in-situ coil implemented in a confocal magnetron sputtering system is used to modify the ion flux impacting the substrate, thereby tuning the ion-to-neutral ratio. Plasma characterization performed at the substrate is used to map the spatial dependence of the ion flux density and the total energy flux density across the substrate holder. In addition, spatially-resolved temperature measurements are performed for different plasma conditions. Aluminum nitride (AlN) thin films were deposited by reactive sputtering in the fully poisoned mode on Si (100) and borosilicate glass substrates using the open field configuration. Texture, growth morphology, and residual stress of the films were determined and correlated with the plasma conditions and substrate temperatures obtained by applying the coil's magnetic field. All AlN films were stoichiometric and showed a hexagonal structure with (001) texture. The film stress was found to change from 0.9 GPa (tensile) to 4 GPa (compressive) with increasing ion flux density. Electron microscopy revealed an evolution from an open grain boundary to a dense film morphology compatible with the observed residual stress dependence of the films on the ion flux. No change in residual stress and film morphology was observed within the 100 °C–500 °C temperature range used here.

Mallinson's idea that some spin textures in planar magnetic structures could produce an enhancement of the magnetic flux on one side of the plane at the expense of the other gave rise to permanent magnet configurations known as Halbach magnet arrays. Applications range from wiggler magnets in particle accelerators and free electron lasers to motors and magnetic levitation trains, but exploiting Halbach arrays in micro- or nanoscale spintronics devices requires solving the problem of fabrication and field metrology below a 100 μm size. In this work, we show that a Halbach configuration of moments can be obtained over areas as small as 1 μm × 1 μm in sputtered thin films with Néel-type domain walls of unique domain wall chirality, and we measure their stray field at a controlled probe-sample distance of 12.0 ± 0.5 nm. Because here chirality is determined by the interfacial Dyzaloshinkii-Moriya interaction, the field attenuation and amplification is an intrinsic property of this film, allowing for flexibility of design based on an appropriate definition of magnetic domains. Skyrmions (100 nm wide) illustrate the smallest kind of such structures, for which our measurement of stray magnetic fields and mapping of the spin structure shows they funnel the field toward one specific side of the film given by the sign of the Dyzaloshinkii-Moriya interaction parameter D.

Magnetic properties of [Co(0.4 nm)/Pt(0.7 nm)] 5 multilayers are tailored by controlling the sputtering voltage during growth of cobalt layers by a facing target cathode. It is shown that increasing sputtering voltage up to 150 V leads to an improved crystalline texture and this results in larger magnetic anisotropies together with increased out-of-plane coercive fields. At a higher cathode voltage of 540 V, however, crystalline texture quality slightly worsens and this is accompanied by a decrease in the effective anisotropy. Using facing target cathode sputtering, the crystalline structure of the multilayers can be controlled without applying any heat treatment and this can be utilized to optimize the magnetic properties of Co/Pt multilayers for specific applications.

Giant exchange bias shifts of several Tesla have been reported in ferrimagnetic/ferromagnetic bilayer systems, which could be highly beneficial for contemporary high energy density permanent magnets and spintronic devices. However, the lack of microscopic studies of the reversal owing to the difficulty of measuring few nanometer-wide magnetic structures in high fields precludes the assessment of the lateral size of the inhomogeneity in relation to the intended application. In this study, the magnetic reversal process of nanoscale exchange-coupled bilayer systems, consisting of a ferrimagnetic TbFeCo alloy layer and a ferromagnetic [Co/Ni/Pt]N multilayer, was investigated. In particular, minor loop measurements, probing solely on the reversal characteristics of the softer ferromagnetic layer, reveal two distinct reversal mechanisms, which depend critically on the thickness of the ferromagnetic layer. For thick layers, irreversible switching of the macroscopic minor loop is observed. The underlying microscopic origin of this reversal process was studied in detail by high-resolution magnetic force microscopy, showing that the reversal is triggered by in-plane domain walls propagating through the ferromagnetic layer. In contrast, thin ferromagnetic layers show a hysteresis-free reversal, which is nucleation-dominated due to grain-to-grain variations in magnetic anisotropy of the Co/Ni/Pt multilayer and an inhomogeneous exchange coupling with the magnetically hard TbFeCo layer, as confirmed by micromagnetic simulations.

High-quality epitaxial Pt _lms are usually grown by molecular beam evaporation (MBE) techniques, where the deposited atoms reach the substrate with typical thermal energies. To obtain a good epitaxial growth, the substrate is kept at elevated temperatures ranging between few hundred to thousand degrees. While the epitaxial quality improves at higher substrate temperatures, above a critical temperature Volmer-Weber growth mode starts and causes a rough _lm morphology. Here, we use a new type of facing target cathode (FTC) to grow Pt onto Al2O3 (0001) substrates. In contrast to conventional sputtering sources, FTC sources provide adatoms with lower kinetic energies, but higher growth rates compared to MBE. In this study, the crystal structure of Pt films is compared for different substrate temperatures. Using FTC, at Pt films with low strain and a morphology that is either nanocrystalline or highly epitaxial could be grown through proper choice of substrate temperature.

Exchange-coupled structures consisting of ferromagnetic and ferrimagnetic layers become technologically more and more important. We show experimentally the occurrence of completely reversible, hysteresis-free minor loops of [Co(0.2 nm)/Ni(0.4 nm)/Pt(0.6 nm)]$_N$ multilayers exchange-coupled to a 20 nm thick ferrimagnetic Tb$_{28}$Co$_{14}$Fe$_{58}$ layer, acting as hard magnetic pinning layer. Furthermore, we present detailed theoretical investigations by means of micromagnetic simulations and most important a purely analytical derivation for the condition of the occurrence of full reversibility in magnetization reversal. Hysteresis-free loops always occur if a domain wall is formed during the reversal of the ferromagnetic layer and generates an intrinsic hard-axis bias field that overcomes the magnetic anisotropy field of the ferromagnetic layer. The derived condition further reveals that the magnetic anisotropy and the bulk exchange of both layers, as well as the exchange coupling strength and the thickness of the ferromagnetic layer play an important role for its reversibility., Comment: 9 pages, 7 figures

Skyrmion imaging and electrical detection via topological Hall (TH) effect are two primary techniques for probing magnetic skyrmions, which hold promise for next-generation magnetic storage. However, these two kinds of complementary techniques have rarely been employed to investigate the same samples. We report the observation of nanoscale skyrmions in SrIrO

High-quality epitaxial Pt films are usually grown by molecular beam evaporation (MBE) techniques, where the deposited atoms reach the substrate with typical thermal energies. To obtain a good epitaxial growth, the substrate is kept at elevated temperatures ranging between few hundred to thousand degrees. While the epitaxial quality improves at higher substrate temperatures, above a critical temperature Volmer-Weber growth mode starts and causes a rough film morphology. Here, we use a new type of facing target cathode (FTC) to grow Pt onto Al 2 O 3 (0001) substrates. In contrast to conventional sputtering sources, FTC sources provide adatoms with lower kinetic energies, but higher growth rates compared to MBE. In this study, the crystal structure of Pt films is compared for different substrate temperatures. Using FTC, flat Pt films with low strain and a morphology that is either nanocrystalline or highly epitaxial could be grown through proper choice of substrate temperature.

Research in new quantum materials requires multi-mode measurements spanning length scales, correlations of atomic-scale variables with macroscopic function, and spectroscopic energy resolution obtainable only at millikelvin temperatures, typically in a dilution refrigerator. In this article, we describe a multi-mode instrument achieving μeV tunneling resolution with in-operando measurement capabilities of scanning tunneling microscopy (STM), atomic force microscopy (AFM), and magnetotransport inside a dilution refrigerator operating at 10 mK. We describe the system in detail including a new scanning probe microscope module design, sample and tip transport systems, along with wiring, radio-frequency (RF) filtering, and electronics. Extensive benchmarking measurements were performed using superconductor-insulator-superconductor (SIS) tunnel junctions, with Josephson tunneling as a noise metering detector. After extensive testing and optimization, we have achieved less than 8 μeV instrument resolving capability for tunneling spectroscopy, which is 5-10 times better than previous instrument reports and comparable to the quantum and thermal limits set by the operating temperature at 10 mK.

Optically transparent, colorless Al-O-N and Al-Si-O-N coatings with discretely varied O and Si contents were fabricated by reactive direct current magnetron sputtering (R-DCMS) from elemental Al and Si targets and O2 and N2 reactive gases. The Si/Al content was adjusted through the electrical power on the Si and Al targets, while the O/N content was controlled through the O2 flow piped to the substrate in addition to the N2 flow at the targets. The structure and morphology of the coatings were studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM), while the elemental composition was obtained from Rutherford backscattering spectrometry (RBS) and heavy ion elastic recoil detection analysis (ERDA). The chemical states of the elements in the coatings were analyzed by X-ray photoelectron spectroscopy (XPS). Based on analytical results, a model describing the microstructural evolution of the Al-O-N and also previously studied Al-Si-N [1, 2, 3, 4] coatings with O and Si content, respectively, is established. The universality of the microstructural evolution of these coatings with the concentration of the added element is attributed to the extra valence electron (e–) that must be incorporated into the AlN wurtzite host lattice. In the case of Al-O-N, this additional valence charge arises from the e – acceptor O replacing N in the AlN wurtzite lattice, while the e – donor Si substituting Al fulfills that role in the Al-Si-N system. In view of future applications of ternary Al-O-N and quaternary Al-Si-O-N transparent protective coatings, their mechanical properties such as residual stress (σ), hardness (HD) and Young’s modulus (E) were obtained from the curvature of films deposited onto thin substrates and by nanoindentation, respectively. Moderate compressive stress levels between −0.2 and −0.5 GPa, which suppress crack formation and film-substrate delamination, could be obtained together with HD values around 25 GPa.

International audience; We have studied the structural and magnetic properties of enhanced-permeability-dielectric FeCo/Al2O3-multilayer thin films deposited on 8 ''-Si wafers in an industrial magnetron sputtering system. The EPD-multilayers consist of 25 periods of alternating nanometer-thick FeCo-layers deposited by DC sputtering from a Fe60Co40 target and Al2O3-interlayers deposited by RF sputtering from an Al2O3 target. We tuned the magnetic properties of these thin films by varying the thickness of FeCo-layers from 1.1nm to 2.1nm, while the thickness of Al2O3-interlayers remained unchanged (3.5nm). The formation of layers of disconnected FeCo-nanoparticles separated by an Al2O3-matrix was revealed by grazing incidence small angle X-ray-scattering. Further insight into the microstructure of these layers was obtained from X-ray-reflectivity, highly asymmetric-X-ray-diffraction and non-coplanar grazing-incidence-diffraction. The Fe/Co ratio in the FeCo-layers obtained from X-ray-fluorescence measurements was (59 +/- 1)/(41 +/- 1), which is in very good agreement with the nominal value in the Fe60C40 target. Using the standing wave technique we found that most of the Fe and Co atoms were located inside the polycrystalline grains, except for a small fraction that diffused into the Al2O3-matrix, and that the thinner the FeCo-layers thickness the higher the fraction of diffused atoms with respect to those in the grains. Zero-field-cooled, field-cooled, and hysteresis (B-H) and (M-H) measurements showed that the FeCo/Al2O3-multilayers with FeCo-layers thinner than 1.7-1.8 nm exhibit superparamagnetic behavior (no coercivity and remanence) at room temperature with peak relative low-field permeability up to 887. By exceeding this critical thickness, the neighboring FeCo-aggregates started to coalesce, and this led to the ferromagnetic behavior revealed by a finite coercivity and remanence in the hysteresis loops.

A class of artifacts manifesting as soft magnetic components are revealed from magnetometry measurements of rare earth-transition metal (TbFe) thin films prepared by magnetron sputtering. They are not inherent to TbFe, but are a direct result of the manner in which the substrates are mounted prior to sample fabrication, with a material deposited at the substrate sides giving rise to a significant magnetic moment. The authors find the same artifacts to also be present in rare earth-free [Co/Pt] multilayers. Trying to supress the appearance of this type of artifact has an influence on the coercivity and, in some cases, on the shape of the reversal curves. Care needs to be taken during fabrication to ensure reliable and reproducible samples so that sensitive magnetic parameters, such as coercivity and compensation points, can be extracted accurately and that data are not misinterpreted for even more complex systems. This type of artifact is not limited to samples prepared by sputtering but can extend to other conventional thin-film deposition methods.

The redistribution of ions in light-emitting electrochemical cells (LECs) plays a key role in their functionality. The direct quantitative mapping of ion density distributions in operating realistic sandwich-type devices, however, has not been experimentally achieved. Here we operate high-performing [Super Yellow/trimethylolpropane ethoxylate/lithium trifluoromethanesulfonate (Li+CF3SO3–)] LEC devices inside a time-of-flight secondary ion mass spectrometer and cool the devices after different operation times to liquid nitrogen temperatures before depth profiling is performed. The results reveal the dependence of the elemental and molecular distributions across the device layer on operation conditions. We find that the ion displacements lead to a substantial shift of the local chemical equilibria governing the free ion concentration.

AlN transparent coatings alternated with different thicknesses of Si3N4 layers were epitaxially grown on single-crystalline α-Al2O3 (0001) substrates by reactive magnetron sputtering, in order to investigate the possibility of stabilization of a crystalline form of silicon nitride. High resolution transmission electron microscopy study of the cross-sections through these coatings revealed that silicon nitride can be epitaxially stabilized in a crystalline form up to breakdown thickness t S i N y e p i of about 0.7–1.0 nm corresponding to ~ 2.5–3.5 monolayers, which is anyway smaller than 1.2 nm (~ 4 monolayers). For t S i N y > t S i N y e p i , amorphous Si3N4 is grown on top of epitaxially stabilized 0.7 nm of crystalline Si3N4 resulting in a mixed growth mode. The influence of the epitaxial stabilization of crystalline Si3N4 on hardness enhancement in the case of the Al–SiN system is compared to the TiN/Si3N4 system and some issues for extrapolation to nanocomposites are discussed

The combination of Time-of-flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Scanning Force Microscopy (SFM) allows the 3D-compositional analysis of samples or devices. Typically, the topographical data obtained by SFM is used to determine the initial sample topography and the absolute depth of the ToF-SIMS analysis. Here ToF-SIMS and SFM data sets obtained on 2 prototypical samples are explored to go beyond conventional 3D-compositional analysis. SFM topographical and material contrast maps are combined with ToF-SIMS retrospective analysis to detect features that would have escaped a conventional ToF-SIMS data analysis. In addition, SFM data is used to extrapolate the chemical information beyond the spatial resolution of ToF-SIMS, allowing the mapping of the chemical composition at the nanoscale.

The microstructure evolution of Al–Si–N coatings with increasing Si content is described based on data from a multi-technique approach with data from X-ray diffraction, SEM, XPS and UV–vis. At Si contents below about 6 at.% Si the coatings form solid solutions of Si in wurtzite (w-) AlN, while at Si concentrations between 6 and 15 at.% Si nanocomposites consisting of a Si-saturated nanocrystalline w-Al–Si–N phase exist with Si 3 N 4 as a tissue phase. The tissue phase formation already starts at 4 at.% Si and is completed at 7 at.%. Values of the refractive index and extinction coefficient as well as data from X-ray diffraction for concentrations up to 12 atomic % (at.%) of Si are consistent with the assumption of an epitaxial Si 3 N 4 tissue phase layer of one monolayer thickness, which separates the w-Al–Si–N nanocrystals from each other in nanocomposites. Silicon contents above ca. 12 at.% lead to the formation of a Si 3 N 4 tissue phase with properties similar to amorphous Si 3 N 4 . A quantitative model is presented that unifies the experimental evidences into a consistent image of the microstructure at different silicon contents.

Accurate charge referencing in XPS of insulating specimens is a delicate issue. This difficulty is illustrated in the case of Al-Si-N composite thin films deposited by reactive magnetron sputtering with variable composition from pure aluminum nitride to pure silicon nitride. The samples were mounted with Au-coated metallic clamps. Argon sputter cleaning was required to remove a surface native oxide before analysis. For charge referencing implanted argon atoms from the sputter gas and a small amount of gold re-deposited from the metallic clamps onto the specimen surface during sputter cleaning were evaluated. For the argon atoms, a surprisingly large chemical shift (∼1 eV) and a significant peak broadening (0.6 eV) of the Ar 2p3/2 photoelectron line were found with varying the Si content of the films. This could be related to chemical and structural changes of the Al-Si-N films. Hence implanted argon could not be used for charge referencing of Al-Si-N samples. In contrast to the implanted argon, the Au 4f7/2 line width of the gold re-deposited onto the sample surface did not depend on the Si content of Al-Si-N films. A constant energy shift (∼1.2 eV) of the Au 4f7/2 line as compared with bulk gold was, however, found, which was related to the size of gold particles formed on the insulating films. Therefore gold could be reliably used to study chemical shifts of sample-relevant species in Al-Si-N films, but the absolute binding energies of Al 2p, Si 2p and N 1s photoelectrons could not be determined. Copyright © 2011 John Wiley & Sons, Ltd.

We report on the design and first tests of a novel instrument aimed at combining the benefits of scanning force microscopy with those of X-ray spectroscopy. For this we built an instrument combining a scanning transmission X-ray microscope with a beam-deflection atomic force microscope in a coaxial geometry. This allows to combine X-ray absorption spectroscopy and high resolution topography in-situ. When replacing the conventional scanning probe tip by a coaxially shielded tip the instrument will allow detection of the photoelectrons produced by resonant X-ray absorption. This could yield spectroscopic information with a spatial resolution approaching the values achievable with atomic force microscopy.

A robust off-resonance intermittent contact mode scanning force microscopy technique suitable for operation under different environmental conditions is presented. The technique relies on a multi-channel lock-in amplifier to measure multiple high harmonic magnitudes and phases. For distance control, the fundamental harmonic magnitude is used. With this, high intermittent contact frequencies become feasible even with older atomic force microscope data acquisition systems with limited measurement bandwidths, provided high frequency tip-sample distance actuation techniques are used. Suitable higher harmonic magnitude images provide a qualitative materials' contrast. If a sufficiently high number of high harmonic magnitudes and phases are recorded, force-distance curves at all imaged points can be reconstructed. From fitting models of the contact mechanics to force versus tip-sample penetration data, the elastic modulus of the sample can be obtained.

Manipulation experiments have been performed with single molecules of the hydrocarbon propene on a copper(211) surface at 7 K. Depending on the location of the methyl group, propene forms two enantiomorphous pairs of different adsorbate states. Beyond repositioning of the molecules via vertical and lateral manipulations with the STM tip, conversions between the different adsorbate geometries were observed. The role of inelastically tunneled electrons and the electric field in the junction between tip and surface are discussed as origins of adsorbate mode conversion. Copyright © 2010 John Wiley & Sons, Ltd.

Pumped up: Propene molecules form chiral complexes when adsorbed on a copper surface. Inelastically scattered tunneling electrons from the tip of a scanning tunneling microscope induce rotation or diffusion of the adsorbate on the surface. Higher tunneling currents can lead to conversion of the adsorbate into the opposite enantiomer.

Chiralitatsumkehr durch Elektronen: Propenmolekule bilden chirale Komplexe bei Adsorption auf einer Kupferoberflache. Inelastisch gestreute Tunnelelektronen aus der Spitze eines Rastertunnelmikroskops regen molekulare Schwingungen an, die zur Rotation oder Diffusion des Adsorbats auf der Oberflache fuhren. Bei hoheren Tunnelstromen wird auch die Umwandlung in die entgegengesetzte Konfiguration beobachtet.

Motivated by the success of transition metal nanocomposite hard coatings, a new optically transparent coating based on the Al–Si–N ternary system was developed. Al–Si–N thin films were deposited by reactive DC magnetron co-sputtering of Al and Si targets in an Ar/N 2 atmosphere at 200 °C and 500 °C sample temperature. The structure and mechanical properties of the coatings were investigated by XPS, XRD, TEM, nanoindentation and mechanical profilometry. The chemical composition was varied from pure AlN to Al–Si–N with 23 at.% of Si. The films are crystalline with the hexagonal AlN structure up to 12–16 at.% of Si as found from XRD and TEM analyses. A shift of X-ray diffraction peaks indicates a substitutional incorporation of silicon in the h-AlN lattice up to a solubility limit identified at 6 at.% of Si. By further increasing the silicon content, a nanocomposite nc -Al 0.44 Si 0.06 N 0.5 / a -SiN x is formed. From TEM analysis it follows that the crystalline material consists of columnar grains composed of crystallites with a (002) texture. The mean crystallite size decreases from 60 nm to about 5 nm upon addition of silicon, as revealed by XRD. Hardness measurements show a diffuse hardness maximum exceeding 30 GPa around 10 at.% of Si. At this value a negligible residual stress in the coating is measured.

Hysteresis and coercivity in ferromagnetic thin films strongly depend on the extent of the domain nucleation and wall motion. Ion irradiation can affect both the number of domain walls existing for a given field history and their mobility. To address these factors, we present a micromagnetic study of magnetisation reversal for non-irradiated and Xe-irradiated 185 nm Ni films at 8.3 K. It is shown that irradiation facilitates reversal domain nucleation and increases the number of pinning centres at least 10-fold, although this does not augment hysteresis. In field magnetic force microscopy (MFM) reveals this to be due to a domain size no larger than the average distance between pinning centres.

Ion-irradiation of ferromagnetic films induces pronounced changes of their microstructure and micromagnetism. The present study is devoted to the changes in the domain structure in 65–75 nm electron-evaporated polycrystalline Ni films due to 200-keV Xe+ or 100-keV Ni+ implantation. For magnetic analysis, we combined magnetic force microscopy (MFM) and magneto-optical Kerr effect (MOKE); X-ray diffraction and Rutherford back-scattering spectroscopy served to characterize the microstructure of the films. After deposition, MFM indicated a pattern of magnetic ripples (with in-plane and perpendicular components of the magnetization). After ion irradiation, MOKE showed almost total in-plane remanence, and MFM confirmed the disappearance of the ripples at room temperature. The magnetic properties were correlated with the ion-induced changes in the strain in the as-deposited and ion-irradiated films.

Reactive sputtering of a single metallic target in a pulsed DC mode is a promising approach for a fast and cost-efficient deposition of thin lead zirconate titanate (PZT) films on an industrial scale. Rapid depth profiling of the coatings is necessary for an efficient optimization of the process parameters. We demonstrate in this paper that glow-discharge optical emission spectroscopy is a valuable instrument meeting these requirements. The results obtained on several coatings which have been thermally treated in various ways indicate basically a high uniformity over the whole coating thickness, with the exception of Pb-enrichment at the surface and at the interface. This is in agreement with results obtained by other techniques reported in the literature. The mechanical properties of our PZT coatings as determined by nanoindentation showed reduced values for the hardness which could be explained by the structural and compositional data of the films.

A metallic target was utilized to produce lead zirconate titanate (PZT) thin films by reactive DC pulsed magnetron sputtering on either Ti/Pt(111)/Ti-coated Si wafers at 490 °C or optical glass fibers at 500 °C. Multicrystalline PZT thin films were obtained by applying both conventional annealing (CA) at 650–720 °C in air and rapid thermal annealing (RTA) at 550–700 °C in vacuum. The morphological, structural, and chemical properties of post-annealed PZT have been examined as a function of the annealing temperature and time. Homogeneous, dense and crack-free specimens were produced by CA at 690 °C for 2 h. Low micro-crack formation was observed when PZT-coated wafers were annealed at 550–700 °C by applying RTA. X-ray photoelectron spectroscopy reveals an excess of Pb in the top layer of the surface. The chemical environments of the elements did not change significantly during annealing. First deposition experiments with optical fibers were conducted. Although CA at 650 °C resulted in the successful formation of PZT, scanning electron micrographs showed blister and crack formation.

Magnetic force microscopy (MFM) measurements were performed on an exchange-biased CoO/(Co/Pt) multilayer sample at 8.0 K. Applying an external magnetic field of up to 7.0 T saturates the ferromagnetic layer and the remaining uncompensated antiferromagnetic spins at the antiferromagnet/ferromagnet interfaces are imaged with high lateral resolution. The coupling between the uncompensated spins and the spins in the ferromagnet are found to be antiferromagnetic. In addition, a method to quantitatively analyze the MFM data is presented which allows the determination of the uncompensated spin density at the AF/FM interfaces. It was found that 7% of the spins at the interfaces are uncompensated and contribute to the exchange biasing.

High-resolution magnetic force microscopy (hrMFM) has been used to investigate the write characteristics of forward and reverse flying heads on perpendicular recording media with soft underlayers. hrMFM has the advantage that it provides much better resolution than the read element of a head, particularly in the cross-track direction. Using a quantitative analysis method, many parameters, such as transition position jitter, transition width and signal-to-noise ratio are estimated from the hrMFM image. Furthermore, these parameters, which can also be measured using a spinstand, are compared to the micromagnetic properties of the transitions, such as track curvature, transition width and the local noise associated with transitions. The results give insights into the recording physics and, in particular, in the write process of shielded and un-shielded write heads in perpendicular recording.

A single-passage, bimodal magnetic force microscopy technique optimized for scanning samples with arbitrary topography is discussed. A double phase-locked loop (PLL) system is used to mechanically excite a high quality factor cantilever under vacuum conditions on its first mode and via an oscillatory tip-sample potential on its second mode. The obtained second mode oscillation amplitude is then used as a proxy for the tip-sample distance, and for the control thereof. With appropriate $z$-feedback parameters two data sets reflecting the magnetic tip-sample interaction and the sample topography are simultaneously obtained., Comment: 4 Pages, 4 Figures