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We present experimental results of pulsed laser interaction with metal (Ni, Fe, Nb) and oxide (TiO2, SrTiO3, BaTiO3) targets. The influence of the laser fluence and the number of laser pulses on the resulting target morphology are discussed. Although different responses for metal and oxide targets to repetitive laser irradiation could be expected due to the different band structures of metals and oxides, the optical response is quite similar for 248-nm laser irradiation. Therefore, the difference in response is largely caused by differences in thermal properties.Metal targets show periodic structures of the order of micrometers after consecutive pulses of laser radiation, while the SrTiO3 and BaTiO3 targets show a flat surface after ablation for relatively low fluences (1.0 Jcm?2). The observed TiO2 target ablation characteristics fall in between those of the ablated metals and perovskites, because ablation results in the presence of Ti-rich material, which shields the underlying toichiometric target material from ablation. The final target morphology is dependent on fluence, number of pulses, and the movement of the target itself (rotating, scanning, or stationary). It can take between 15 and 75 pulses to reach a steady-state target morphology on a stationary target.

Transmission electron microscopy is used to evaluate different deposition techniques, which optimize the microstructure and physical properties of superconducting thin films. High-resolution electron microscopy proves that the use of an YBa/sub 2/Cu/sub 2/O/sub x/ buffer layer can avoid a variable interface configuration in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin films grown on SrTiO/sub 3/. The growth can also be controlled at an atomic level by using sub-unit cell layer epitaxy, which results in films with high quality and few structural defects. Epitaxial strain in Sr/sub 0.85/La/sub 0.15/CuO/sub 2/ infinite layer thin films influences the critical temperature of these films, as well as the microstructure. Compressive stress is released by a modulated or a twinned microstructure, which eliminates superconductivity. On the other hand, also tensile strain seems to lower the critical temperature of the infinite layer.

The phase of the macroscopic electron-pair wavefunction in a superconductor can vary only by multiples of 2pi when going around a closed contour. This results in quantization of magnetic flux, one of the most striking demonstrations of quantum phase coherence in superconductors. By using superconductors with unconventional pairing symmetry, or by incorporating pi-Josephson junctions, a phase shift of pi can be introduced in such loops. Under appropriate conditions, this phase shift results in doubly degenerate time-reversed ground states, which are characterized by the spontaneous generation of half quanta of magnetic flux, with magnitude 1/2 Phi(0)(Phi(0) = h/2e = 2.07 x 10(-15) Wb) (ref. 7). Until now, it has only been possible to generate individual half flux quanta. Here we report the realization of large-scale coupled pi-loop arrays based on YBa2Cu3O7-Au-Nb Josephson contacts. Scanning SQUID (superconducting quantum interference device) microscopy has been used to study the ordering of half flux quanta in these structures. The possibility of manipulating the polarities of individual half flux quanta is also demonstrated. These pi-loop arrays are of interest as model systems for studying magnetic phenomena--including frustration effects--in Ising antiferromagnets. Furthermore, studies of coupled pi-loops can be useful for designing quantum computers based on flux-qubits with viable quantum error correction capabilities.

A study is presented on pulsed-laser deposition of thin films of Ba1−xKxBiO3−δ (BKBO) and its parent compound BaBiO3−δ (BBO). BKBO is a non-cuprate high-TC (30 K) superconductor with relatively long coherence length (5 nm) and shows BCS like behavior. Therefore, BKBO is an attractive candidate for superconducting electronic device applications. Furthermore, the insulator BBO is suitable as barrier material. We deposited BKBO thin films from potassium-overdoped targets (Ba0.6K0.8BiO3−δ) in order to compensate for the volatility of potassium in our efforts to obtain superconducting Ba1−xKxBiO3−δ (x=0.3–0.4) thin films. The deposition parameters and annealing procedure were optimized to achieve good quality films. Especially, the substrate temperature is important, because it influences simultaneously the content of potassium and crystallinity of the growing film. This combination hampers the optimization, because they cannot be controlled independently. Furthermore, we will present our first attempts to control the stoichiometry using intervals of different pulsed-laser repetition rates.

High-resolution electron microscopy is used to study the initial growth of different REBa2Cu3O7−δ thin films. In DyBa2Cu3O7−δ ultra-thin films, deposited on TiO2 terminated SrTiO3, two different types of interface arrangements occur: bulk–SrO–TiO2–BaO–CuO–BaO–CuO2–Dy–CuO2–BaO–bulk and bulk–SrO–TiO2–BaO–CuO2–Dy–CuO2–BaO–CuO–BaO–bulk. This variable growth sequence is the origin of the presence of antiphase boundaries. In Nd1+xBa2−xCu3O7−δ thin films, antiphase boundaries tend to annihilate by the insertion of extra Nd-layers. This annihilation is correlated with the flat morphology of the film and the absence of growth spirals at the surface of the Nd-rich films.

A thin interlayer is incorporated in ramp-type Josephson junctions to obtain an increased transparency. The interlayer restores the surface damaged by ion milling and has the advantage of an all in situ barrier deposition between two superconductors, leading to clean and well-defined interfaces. The method has been applied to Josephson junctions between high (YBa2Cu3O7–) and low temperature (Nb) superconductors, separated by a Au barrier. Transmission electron microscopy images of these junctions reveal crystalline YBa2Cu3O7– up to the interface with the Au barrier. The junctions have improved critical current density values exceeding 20 kA/cm2, normal state resistances of 3×10–8 cm2 and IcRn products of 0.7 mV at 4.2 K. Furthermore, the junction properties can be controlled by varying the Au barrier thickness.

Integration of PbZr0.52Ti0.48O3 (PZT) films on glass substrates is of high importance for device applications. However, to make use of the superior ferro- and piezoelectric properties of PZT, well-oriented crystalline or epitaxial growth with control of the crystal orientation is a prerequisite. In this article, we report on epitaxial growth of PZT films with (100)- and (110)-orientation achieved by utilizing Ca2Nb3O10 (CNO) and Ti0.87O2 (TO) nanosheets as crystalline buffer layers. Fatigue measurements demonstrated stable ferroelectric properties of these films up to 5 × 109 cycles. (100)-oriented PZT films on CNO nanosheets show a large remnant polarization of 21 μC/cm2 that is the highest remnant polarization value compared to (110)-oriented and polycrystalline films reported in this work. A piezoelectric response of 98 pm/V is observed for (100)-oriented PZT film which is higher than the values reported in the literature on Si substrates.

Distinct MnO6 octahedral distortions near and away from the La0.67Sr0.33MnO3/SrTiO3(001) (LSMO/STO) interface are quantified using synchrotron x-ray diffraction and dynamical x-ray diffraction simulations. Three structural regions of stress accommodation throughout the film thickness were resolved: near the LSMO/STO interface, intermediate region farther from the interface, and the main layer away from the interface. The results show that within the first two unit cells stress is accommodated by the suppression of octahedral rotations in the film, leading to the expansion of the c-axis lattice parameter. Farther from the interface film structure acquires octahedral tilts similar to thicker perovskite films under tensile stress, leading to a reduced c-axis parameter. We demonstrate that these regions are related to two different strain coupling mechanisms: symmetry mismatch at the interface and lattice mismatch in the rest of the film. The findings suggest new routes for strain engineering in correlated perovskite heterostructures.

Epitaxial Pb(Mg1/3Nb2/3)O3-PbTiO3 200 nm thick, (001) oriented, perovskite phase-pure films were grown on a range of PbZr1−xTixO3 buffer layers (x = 0.2–0.8) and sandwiched between SrRuO3 electrodes on (001) SrTiO3 substrates to form a ferroelectric capacitor structure. Devices without a buffer layer or with a buffer layer of highly tetragonal PbZr1−xTixO3 show very large self-bias fields up to 1.0 × 107 V/m. These self-bias fields correlate with strain gradient layers near the bottom electrode observed in these devices only. The large self-bias was explained quantitatively in terms of the flexoelectric effect.

In this study, we aim to synthesize novel materials that show ferromagnetic and ferroelectric properties with the magnetoelectric effect at room temperature. Nine types of superlattice were fabricated by stacking [7 units — ABO3/7 units — REMO3] for 14 times by pulsed laser deposition. From all reciprocal space mappings (RSMs) of the CaMnO3 (CMO) superlattices, the satellite peaks were clearly observed. The calculated in-plain lattice parameter was 0.382 nm longer than 0.3732 nm, which is the bulk CMO and in-plain lattice parameter of the CMO thin film grown on SrTiO3 (001) substrate. All the CaFeO3 (CFO) series superlattices showed that the satellite peaks and Laue oscillations were clearly observed from the XRD 2θ–θ spectra. In the case of [CFO/BiFeO3 (BFO)] superlattices, the number of deposited units of CFO in [CFO/BFO] one cycle was 6.94, which was quite close to the seven units that we aimed. The in-plain lattice constant of all the CFO series superlattices was fitted to that of the substrate. From RSMs of the [LaMnO3 (LMO)/BFO] superlattice, the lattice parameter of the superlattice was fitted to that of the substrate in-plain. The cube-on-cube growth was confirmed in these LMO series superlattices

Piezoelectrical, ferroelectrical, and structural properties of epitaxial pseudocubic (110)pc oriented 500 nm thick PbZr1−xTixO3 thin films, prepared by pulsed laser deposition on (001) silicon substrates, were measured as a function of composition. The dependence of the measurement data on the Ti content is explained by an abrupt transition from the rhombohedral r-phase to the tetragonal (c/a) 45 phase for x ≈ 0.6, indicating a shift of the Morphotropic Phase Boundary to this value, where the effective piezoelectric coefficient e3 1 ,eff and dielectric constant e33 ,eff reach their maximum values. These findings are of great significance for Si-based piezo-micro electro mechanical systems, in particular energy harvesters. The largest value of the figure-of-merit for such devices was found for x = 0.6, FOM=24.0 GPa

Superconducting thin films have been prepared on Si-substrates, using pulsed laser deposition from a target composed of a mixture of Mg and MgB2 powders. The films were deposited at room temperature and post-annealed at 600 degrees C. The zero resistance transition temperatures were 12 K, with an onset transition temperature of 27 K. Special care has been taken to avoid oxidation of Mg in the laser plasma and deposited film, by optimizing the background pressure of Ar gas in the deposition chamber. For this the optical emission in the visible range from the plasma has been used as indicator. Preventing Mg from oxidation was found to be essential to obtain superconducting films.

After the discovery of the perovskite high Tc superconductors in 1986, a rare and almost unknown deposition technique attracted attention. Pulsed laser deposition (PLD), or laser ablation as it was called in the beginning, became popular because of the possibility to deposit complex materials, like perovskites, as thin film. By introducing in situ diagnostics and control of the laser fluence, PLD became a technique for several experimental studies of diverse complex materials. Nowadays, first steps towards industrial applications of PLD thin films on large wafers, up to 200 mm, are underway. In this paper we give a brief overview of the progress that PLD has made in our research group in Twente. Starting with control of deposition parameters, via in situ diagnostics with reflection high-energy electron diffraction and ending with the latest development in equipment for large-area deposition.

The terminating layer of a perovskite (0 0 1) ABO3 crystal, with A as an alkaline earth metal and B as a transition metal, influences the characteristics of the surface. The morphology during thermal treatment of the surface and epitaxial growth are determined by the composition of the surface, i.e., whether it is BO2, AO, or a mixed-terminated surface. Since the morphology of a thin film is the result of the evolution of the surface during deposition, control from the very first layer is essential for smooth films. In the case of perovskite materials, this means control of the terminating layer. Here, we study the SrTiO3 surface as a model system and the effects of the composition of the terminating layer, determined by the treatment and/or deposition of SrO and TiO2, on homo-epitaxial and hetero-epitaxial growth of SrCuO2 and YBa2Cu3O7. A single-terminated surface turns out to be optimal with respect to a smooth morphology and perfect epitaxy of high-Tc superconducting materials.

In oxide electronics substrates with atomically flat terraces are a request for growing high-quality epitaxial thin films. In this paper results on chemical etching of some substrates with perovskite, ABO3, structure (e.g., SrTiO3, LSAT - the (LaAlO3)0.3(Sr2AlTaO6)0.35 solid solution, and NdGaO3) are presented. In order to obtain high quality substrates, different etchants (NH4F + HF, HCl + NH4Cl, and HCl + HNO3) with various pH values have been studied. From Atomic Force Microscopy (AFM), in air, we conclude that, irrespective of the etchant that has been used, a substrate surface with a BOx terminated layer and atomically flat terraces without etch pits could be obtained. The pH-value and temperature of the etchant and the etching time, however, influence significantly the surface quality. Reflection high energy electron diffraction (RHEED) patterns confirmed the AFM results.

An atomic force microscope has been used to create nanoscale field-effect transistors and other electronic devices at the interface between two different oxide materials.

A method of writing and erasing conducting nanostructures at the interface between the wide-bandgap insulators LaAlO3 and SrTiO3 is presented. New developments for ltrahigh-density information storage look feasible

Pulsed Laser Deposition (PLD) has developed from a fast but limited preparation tool towards a competitive thin film deposition technique. One of the advantages above other techniques is the possibility to growth at relative high background pressure, with a large freedom in choosing the kind of gas. In a number of applications, the gaseous species in the background pressure even are part of the elements to be grown. An evidence example is oxygen in the case of high Tc superconductors and giant magnetic resistors. However, the benefit of relative high pressures hampers the use of standard diagnostics and monitor techniques, e.g. Reflective High Energy Electron Diffraction (RHEED), used for thin film growth. With the possibility to use RHEED at standard PLD pressures it became possible to study the growth of oxide materials under different oxygen and temperature conditions. Here, we present the results on applying this technique on SrTiO 3 , which can be grown in different growth modes, depending on temperature and oxygen pressure, during growth. Applying a modified etch technique to SrTiO 3 single crystals, we were able to grow homo-epitaxial SrTiO 3 in a real 2D growth mode. Additional to the usual information obtained with RHEED, another phenomena can be observed. The pulsed way of deposition, characteristic for PLD, leads to relaxations in the intensity of the diffracted pattern. This is caused by the mobility of the deposited material from a disordered distribution till an ordered one. These relaxation times give extra information about relaxation, crystallization, and nucleation of the deposited material. The results obtained from the intensity oscillations as well as relaxations, has led to a different approach to deposit these complex oxide materials, so-called interval deposition. In this contribution first results on this interval deposition will be presented.

The initial growth of pulsed laser deposited SrTiO3 on SrTiO3 has been studied using high pressure Reflection High Energy Electron Diffraction (RHEED) and Atomic Force Microscopy (AFM). For this, we developed a Pulsed Laser Deposition (PLD)-RHEED system, with the possibility to study the growth and to monitor the growth rates, in situ, at typical PLD pressures (10-50 Pa). Using perfect single crystal SrTiO3 substrate surfaces, we observe true 2D intensity oscillations at different temperatures. Simultaneously, information on the diffusion of the deposited material on the surface could be extracted from the relaxation of the intensity after each laser pulse. The characteristic times depend on pressure and temperature as well as the 2D coverage during growth.

Several groups have monitored the growth of complex oxides in-situ using Reflection High Energy Electron Diffraction (RHEED). In order to utilize RHEED during growth, films are deposited at low background oxygen pressures. Because of the low oxidation power at low pressures, low substrate temperatures have to be used. This hampers, in general, the film crystallinity. Furthermore, the background pressure in Pulsed Laser Deposition (PLD) is an important parameter, because it influences the shape and size of the plasma and, therefore, the deposition rate and homogeneity of the film.We have developed a high-pressure RHEED system, which can be used for growth monitoring during the deposition of complex oxides at standard PLD conditions. Clear diffraction patterns are observable up to 50 Pa, due to the minimized scattering losses.SrTi03 substrate treatments as well as growth studies of Yba2Cu3O7−δ, using atomic layers of SrO or BaO as a buffer-layer, will be discussed in this contribution. It will be shown that monitoring and control of thin film growth by PLD on an atomic level is feasible, even in quite high background pressures.

Artificial materials made from oxide building blocks turn out to be excellent ferroelectrics. This shows that materials with specific properties can be designed by atomic-scale tailoring of their composition.

Epitaxial PbZr0.52Ti0.48O3 (PZT 52/48) heterostructures incorporating SrRuO3 electrodes were patterned through a single step epitaxial lift-off technique without using any acidic etching. This procedure enables patterning of high temperature grown perovskite multilayers through the use of a pre-patterned AlOx mask which acts as a high temperature sacrificial template. Ferroelectric properties of structured PZT grown on (001) SrTiO3 substrates as well as on commercially important platinized Si were investigated in capacitor configuration analogous to structures previously prepared through wet etching. In addition, the patterning technique is shown to be compatible with e-beam lithography for preparation of sub-micron device structures consisting of ferroelectric perovskite materials.

The method used by SolMateS to determine the effective piezoelectric coefficient d31,eff of Pb(Zr,Ti)O3 (PZT) thin films from cantilever displacement measurements is described. An example from a 48 cantilever dataset using different cantilever widths, lengths and crystal alignments is presented. It is shown that for the layer stack of our cantilevers, the multimorph model is more accurate compared to the bimorph model for the d31,eff determination. Corrections to the input parameters of the model are further applied in order to reduce the geometrical error of the cantilever that is caused by its design and processing, as well as correction to the measured tip displacement caused by resonance amplification. It is shown that after these corrections, the obtained d31,eff values are still up to 10% uncertain as the plate behavior and the non-constant radius of curvature of the cantilevers lead to inconsistent results. We conclude that quantitative determination of d31,eff from the cantilevers is highly subjective to misinterpretation of the models used and the measurement data. The true value of d31,eff was determined as −118.9 pm V−1.

Stability issues in thermoelectric NaxCoO2 thin films have been solved by the addition of an in situ amorphous AlOx capping layer, which prevents previously reported degradation when exposed to air. These chemically stable thin films enable detailed analysis of the intrinsic thermoelectric properties and form a significant progress towards applications. Single phase NaxCoO2 thin films with a low surface roughness are grown by pulsed laser deposition with either an epitaxial or textured crystal structure on Al2O3(001) or LaAlO3(001) single crystal substrates, respectively. For textured thin films a resistivity and thermopower of 0.99 mΩ cm and 69 μV K−1 are observed at room temperature, respectively. Based on an estimated thermal conductivity for thin films, the dimensionless figure of merit is very comparable to NaxCoO2 single crystals, demonstrating the effectiveness of the developed capping layer.

We studied the resonant diffraction signal from stepped surfaces of SrTiO3 at the Ti 2p -> 3d (L2,3) resonance in comparison with x-ray absorption (XAS) and specular reflectivity data. The steps on the surface form an artificial superstructure suited as a model system for resonant soft x-ray diffraction. A small step density on the surface is sufficient to produce a well defined diffraction peak, showing the high sensitivity of the method. At larger incidence angles, the resonant diffraction spectrum from the steps on the surface resembles the spectrum for specular reflectivity. Both deviate from the XAS data in the relative peak intensities and positions of the peak maxima. We determined the optical parameters of the sample across the resonance and found that the differences between the XAS and scattering spectra reflect the different quantities probed in the different signals. When recorded at low incidence or detection angles, XAS and specular reflectivity spectra are distorted by the changes of the angle of total reflection with energy. Also the step peak spectra, though less affected, show an energy shift of the peak maxima in grazing incidence geometry.

Obtaining atomically smooth surfaces and interfaces of perovskite oxide materials on polar (111) surfaces presents a particular challenge as these surfaces and interfaces will reconstruct. Here, the effect of the use of screening buffer layers on the epitaxial growth on such polar surfaces is investigated. Both transmission electron microscopy and in situ reflective high energy electron diffraction data imply that the buffer layers, SrRuO3 or LaAlO3, restore a near bulk-like termination at growth temperature, allowing for coherent growth of BiFeO3 and CaTiO3 for all deposited unit cell layers of the film material. An important crystalline orientation in the perovskite system, in terms of the ability to use strain engineering and to fabricate superlattices, is the (111) direction (A schematic drawing of a (111) oriented perovskite is shown in Figure 1(a)). For example, if superlattices of perovskites are grown in the (111) orientation, it is possible to build artificial double perovskites.1,2 Another example is work done by Xiao et al.,3 which shows that it is possible to build a topological insulator by growing in the (111) direction. A lot of knowledge within the field of oxide thin films has been gained by the many heteroepitaxial systems involving cubic (001) substrates like SrTiO3 in which case the surface and interface with the film perovskite structure has been well studied. From these studies, it has become clear that a good perovskite substrate surface fulfills three important criteria: (1) single termination; (2) a stable interface with air/vacuum without major reconstructions; and (3) a stable interface with the film material.

This research presents the deposition and device fabrication of epitaxial Pb(Zr,Ti)O 3 (PZT) thin films for applications in microelectromechanical systems (MEMS). A piezoelectric micro-membrane is described as an example. Using the pulsed laser deposition (PLD) technique and the MEMS microfabrication process, the piezo-membranes with diameters ranging from 200 to 500 μm were obtained. The displacement of piezo-membranes increased from 5.1 to 17.5 nm V −1 with a piezoelectric-membrane diameter in the range of 200–500 μm. Furthermore, the effect of PZT film-thickness on the mechanical properties has been investigated. By using the conductive-oxide SrRuO 3 (SRO) layers as the electrodes, the degradation of both ferroelectric and piezoelectric properties is prevented up to 1010 switching cycles.

Owing to the superior dielectric property of aluminum oxide, precise patterning of self-assembled monolayers (SAMs) and nanoparticles (NPs) on aluminum oxide substrates is highly interesting for generating SAM- or NP-based electronic devices. This study employed nanoimprint lithography (NIL) and nanomolding in capillaries (NAMIC) for patterning ferromagnetic NPs on aluminum oxide substrates. We demonstrated the fabrication of structured arrays of various SAMs and NPs in micrometre and nanometre ranges. The polymer template generated by NIL behaved as a physical barrier and defined the pattern areas on the substrate. FePtAu NPs were assembled on phosph(on)ate SAM-modified polymer patterned substrates. After polymer removal, nano- and microscale line and dot NP patterns, with controlled layer thickness, were obtained on aluminum oxide substrates. Thick nanolines of NPs were obtained by NAMIC. PO3-terminated FePtAu NPs were assembled on alumina without need of a linker. The magnetic properties of the NPs were addressed by vibrating sample magnetometry and those of the patterned NPs by magnetic force microscopy.

The magnetic behavior of La 0.67 Sr 0.33 MnO 3 (LSMO) filmsgrown on SrTiO 3 (110) substrates was studied. In-plane uniaxial magnetic anisotropy with the easy axis aligned with the [001] lattice direction was observed, together with an out-of-plane component. This is explained by the crystal structure of the films, which shows a tilt of the (001) planes. This tilt creates a long body diagonal which forces the easy axis out-of-plane and results in magnetic domain formation. The domain size is estimated at 500 nm. The switching behavior of the magnetization is well described by a two-phase model which takes both coherent rotation and domain wall motion into account. These results are of importance for the application of LSMO in tunnel magnetoresistance devices, where the (110) orientation is preferred because of the reduction in the dead layer in this direction

We report an anisotropic misfit stress relief mechanism in thin La0.67Sr0.33MnO3 (LSMO) films coherently grown on NdGaO3(110) substrates. These results are uniquely related to the orthorhombicity of the LSMO. The x-ray diffraction measurements and quantitative simulations demonstrate that biaxial mismatch stress is relieved differently along in-plane directions perpendicular to each other: in the [1math0] direction stress is accommodated by decrease of the γ angle of the orthorhombic LSMO unit cell, while in the [001] direction stress is partially relieved by periodic lattice modulations.

Ferroelectric Pb(ZrxTi1−x)O3 sandwiched between SrRuO3 electrodes devices were fabricated by a single stencil deposition method. By varying the pressure, the dimension of the deposited pattern could be controlled. The dimension becomes larger in the high pressure shockwave regime, which is typical for pulsed laser deposition. The particle interactions result in an increased amount of broadening. At lower pressures, the deposited material is still in the correct crystalline phase and broadening is minimized. Top electrodes are isolated from the bottom electrode by controlling the broadening of the ferroelectric medium. With this method, multilayered oxide devices can be created in situ

Atomic force microscopy (AFM) is one of the most important tools in nanotechnology and surface science. Because of recent developments, nowadays, it is also used to study dynamic processes, such as thin film growth and surface reaction mechanisms. These processes often take place at high temperature and there is a clear need to extend the current operating temperature range of AFM. This letter describes a heating stage and a modified AFM that extends the maximum operating temperature to 750°C. Atomic step resolution is obtained up to 500°C in ambient and even up to 750°C in vacuum.

Ferroelectrics display spontaneous and switchable electrical polarization. Until recently, ferroelectricity was believed to disappear at the nanoscale; now, nano-ferroelectrics are being considered in numerous applications. This renewed interest was partly fuelled by the observation of ferroelectric domains in films of a few unit cells thickness, promising further size reduction of ferroelectric devices. It turns out that at reduced scales and dimensionalities the material's properties depend crucially on the intricacies of domain formation, that is, the way the crystal splits into regions with polarization oriented along the different energetically equivalent directions, typically at 180o and 90o from each other. Here we present a step forward in the manipulation and control of ferroelectric domains by the growth of thin films with regular self-patterned arrays of 90o domains only 7 nm wide. This is the narrowest width for 90o domains in epitaxial ferroelectrics that preserves the film lateral coherence, independently of the substrate., Comment: 9 pages (4 two-column text pages + 4 figures + 1 supplementary figure). Source is 1 TeX file + 5 figures in PDF format

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Superconducting quantum interference devices SQUIDs and magnetometers are fabricated from nanoconstrictions in epitaxial MgB2 films. The nanobridges are contained within single-crystalline grains, resulting in clean transport, a large critical current density of 5107 A/cm2 at 4.2 K, and stable SQUID voltage modulation up to 38.8 K. The magnetometer is realized with an inductively coupled pickup loop, giving rise to a field sensitivity of 1 pT Hz¿1/2 down to 1 Hz. The device properties are governed by the two-band superconducting nature of MgB2, posing, however, no problems to a successful development of boride magnetic field sensing devices. The MgB2 zero-temperature London penetration depth is measured to be 62 nm, close to theoretical predictions.

At the end of a rush lasting over half a century, in which CMOS technology has been experiencing a constant and breathtaking increase of device speed and density, Moore’s law is approaching the insurmountable barrier given by the ultimate atomic nature of matter. A major challenge for 21st century scientists is finding novel strategies, concepts and materials for replacing silicon-based CMOS semiconductor technologies and guaranteeing a continued and steady technological progress in next decades. Among the materials classes candidate to contribute to this momentous challenge, oxide films and heterostructures are a particularly appealing hunting ground. The vastity, intended in pure chemical terms, of this class of compounds, the complexity of their correlated behaviour, and the wealth of functional properties they display, has already made these systems the subject of choice, worldwide, of a strongly networked, dynamic and interdisciplinary research community. Oxide science and technology has been the target of a wide four-year project, named Towards Oxide-Based Electronics (TO-BE), that has been recently running in Europe and has involved as participants several hundred scientists from 29 EU countries. In this review and perspective paper, published as a final deliverable of the TO-BE Action, the opportunities of oxides as future electronic materials for Information and Communication Technologies ICT and Energy are discussed. The paper is organized as a set of contributions, all selected and ordered as individual building blocks of a wider general scheme. After a brief preface by the editors and an introductory contribution, two sections follow. The first is mainly devoted to providing a perspective on the latest theoretical and experimental methods that are employed to investigate oxides and to produce oxide-based films, heterostructures and devices. In the second, all contributions are dedicated to different specific fields of applications of oxide thin films and heterostructures, in sectors as data storage and computing, optics and plasmonics, magnonics, energy conversion and harvesting, and power electronics., The authors acknowledge financial support from the Netherlands Organization for Scientific Research (NWO). We acknowledge fruitful interactions with our many collaborators in the realm of artificial quantum materials, especially the groups of J.C. Séamus Davis, Craig J. Fennie, Eun-Ah Kim, Lena F. Kourkoutis, and David A. Muller. This work was supported by the National Science Foundation (Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM)) under Cooperative Agreement No. DMR-1539918. Financial support from the Spanish Ministry of Economy and Competitiveness (SEV-2015-0496, MAT2014-56063-C2-1-R, and MAT2017-85232-R), from Generalitat de Catalunya (2014 SGR 734), and from Slovenian Research Agency (P2-0091 and J2-6759) is acknowledged. The authors acknowledge funding from the EPSRC grant EP/ P027032/1. Prof. O. Nilsen is acknowledged for valuable discussions on the current status of ALD perovskites. Author thanks fruitful discussions with Dr. J. Santiso. Financial support from the Spanish Ministry of Economy and Competitiveness through the ''Severo Ochoa" Programme for Centres of Excellence in R&D (SEV-2015-0496), and projects MAT2015-71664-R and MAT2015- 67593-P is acknowledged. This work was supported by PARADIM, a National Science Foundation Materials Innovation Platform (Grant DMR-1539918), and by the Air Force Office of Scientific Research (Award number FA 9550-16-1-0305). Funding from the DFG (German Science Foundation) within the collaborative research center SFB 917 'Nanoswitches' and the W2/ W3 program of the Helmholtz association is gratefully acknowledged. We furthermore acknowledge funding by the ToBE CoST action (MP1308). We acknowledge financial support from the ERC Consolidator grant ‘‘MINT” (contract number n° 615759) and the ANR project ‘‘FERROMON”. This publication has received funding from the European Union’s Horizon 2020 research innovation programme under grant agreement 732642 (ULPEC project). This work is supported by a public grant overseen by the French National Research Agency (ANR) as part of the ‘‘Investissements d’Avenir” program (Labex NanoSaclay, reference: ANR-10-LABX-0035). This work was supported in part by the EFRE fund of the European Commission, by the Free State of Saxony (Germany), and by funding of the Deutsche Forschungsgemeinschaft (DFG project: Inferox). This work was supported in parts by the Deutsche Forschungsge-meinschaft (DFG) under Grant SFB 917 ''Nanoswitches" and the COST Action MP1308 ''TO-BE (Towards Oxide-Based Electronics)". This publication has received funding from the European Union’s Horizon 2020 research innovation programme under grant agree-ment 732642 (ULPEC project). We thank M. Belmoubarik and J. Uzuhashi for their technical assistance for Fig. 36. We acknowledge support from the ImPACT Program of Council for Science, Technology and Innovation, Japan. Gervasi Herranz acknowledges financial support from MAT2014-56063-C2-1-R and Severo Ochoa SEV-2015-0496 Projects, and the Generalitat de Catalunya (2014 SGR 734Project). Pablo Sanchis acknowledges financial support from TEC2016-76849 and FP7-ICT-2013-11-619456 SITOGA. We thank the financial support from the SNSF NRP70 ‘‘Energy Turnaround” and GRAPHENE project supported by the European Commission Seventh Framework Programme under contract 604391 is gratefully acknowledged. To the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV-2013-0295; for the grant ENE2016-79282-C5-2-R and the OrgEnergy Excelence NetworkCTQ2016-81911-REDT. To the Agència de Gestió d’Ajuts Universitaris i de Recerca for the support to the consolidated Catalonia research group 2014SGR-1212 and the Xarxa de Referència en Materials Avançats per a l’Energia (Xarmae). To the CERCA Pro-gramme/Generalitat de Catalunya and to the European COST Action StableNextSol project MP1307. The authors would like to acknowledge the financial support from ACCIO-Generalitat de Catalunya and the European Union for the 3D-PHOTOXIDES ERA-NET MANUNET II and from IV Fondo de Emprendedores of Fundación Repsol for the SOLAR OXIDES project. The authors would also thank Mr. Andrés Gómez from Institut de Ciència de Materials de Barcelona (ICMAB) for the pc-AFM measure-ments and Mr. Alex Hernández from Institut de Recerca en Energia de Catalunya (IREC) for the sputtering and valuable guidance. We would like to acknowledge the financial support granted by the Spanish Government [Projects MAT2014-56063-C2-1-R, MAT2015-73839-JIN, MAT2014-51778-C2-1-R and MAT2014-57960-C3-1-R, and associated FEDER], I.F. acknowledges Ramon y Cajal contract RYC-2017-22531, the Generalitat de Catalunya (2014-SGR-734). ICMAB-CSIC authors acknowledge financial support from the Spanish Ministry of Economy and Competitiveness, through the ‘‘Severo Ochoa” Program for Centers of Excellence in R&D (SEV-2015-0496). C.P. and B.D. acknowledge a public grant overseen by the French National Research Agency (ANR) as part of the ‘‘Investissements d’Avenir” program (Grant No. ANR-10-LABX-0035, Labex NanoSaclay). The authors would like to acknowledge L. Pereira and P. Bar-quinha for fruitful discussions during the manuscript preparation. We acknowledge the funding from Portuguese Foundation for Science and Technology, Reference UID/CTM/50025/2013 and FEDER funds through the COMPETE 2020 Programme under the project number POCI-01-0145-FEDER-007688. Part of this work is partially financed from European Community H2020 program under grant agreements No. 665046 (project Symbiotic) and No. 644631 (project Roll-Out). Several of the recent advances in electrochromic and ther-mochromic materials, reported above, were reached with financial support received from the European Research Council under the European Community’s Seventh Framework Program (FP2007– 2013)/ERC Grant Agreement No. 267234 (‘‘GRINDOOR”).

Plume generation and the effects of the plume on the welding process and three methods for suppression of the plume are discussed. An experimental nozzle for Nd-YAG laser welding is presented. The nozzle is used for welding experiments with Stainless Steel and Titanium. Results show that the nozzle is suited for creation of a shielding gas atmosphere and for protection of optic components. No significant effect of the plume suppression is found. This may be due to the low power densities used throughout the experiments.