Evaluation of Sputtering Processes in Strontium Iridate Thin Films.

The growth of epitaxial thin films from the Ruddlesden-Popper series of strontium iridates by magnetron sputtering is analyzed. It was found that, even using a non-stoichiometric target, the films formed under various conditions were consistently of the perovskite-like n = ∞ SrIrO phase, with no evidence of other RP series phases. A detailed inspection of the temperature-oxygen phase diagram underscored that kinetics mechanisms prevail over thermodynamics considerations.

Spin-to-Charge Conversion in All-Oxide LaSrMnO/SrIrO Heterostructures.

Spin injection and spin-charge conversion processes in all-oxide LaSrMnO/SrIrO (LSMO/SIO) heterostructures with different SIO layer thickness and interfacial features have been studied. Ferromagnetic resonance (FMR) technique has been used to generate pure spin currents by spin pumping (SP) in ferromagnetic (FM) half-metallic LSMO. The change of the resonance linewidth in bare LSMO layers and LSMO/SIO heterostructures suggests a successful spin injection into the SIO layers.

X-ray Absorption Spectroscopy Study of Thickness Effects on the Structural and Magnetic Properties of PrNiMnO Double Perovskite Thin Films.

In this work, we report a systematic study of the influence of film thickness on the structural and magnetic properties of epitaxial thin films of PrNiMnO (PNMO) double perovskite grown on top of two different (001)-SrTiO and (001)-LaAlO substrates by RF magnetron sputtering. A strong dependence of the structural and magnetic properties on the film thickness is found. The ferromagnetic transition temperature () and saturation magnetization (s) are found to decrease when reducing the film thickness.

Optimization of the Growth Process of Double Perovskite PrNiMnO Epitaxial Thin Films by RF Sputtering.

Epitaxial thin films of PrNiMnO (PNMO) double perovskite were grown on (001)-oriented SrTiO substrates by RF magnetron sputtering. The influence of the growth parameters (oxygen pressure, substrate temperature, and annealing treatments) on the structural, magnetic and transport properties, and stoichiometry of the films was thoroughly investigated. It is found that high-quality epitaxial, insulating, and ferromagnetic PNMO thin films can only be obtained in a narrow deposition parameter window.

Suppression of spin rectification effects in spin pumping experiments.

Spin pumping (SP) is a well-established method to generate pure spin currents allowing efficient spin injection into metals and semiconductors avoiding the problem of impedance mismatch. However, to disentangle pure spin currents from parasitic effects due to spin rectification effects (SRE) is a difficult task that is seriously hampering further developments. Here we propose a simple method that allows suppressing SRE contribution to inverse spin Hall effect (ISHE) voltage signal avoiding long and tedious angle-dependent measurements.

Formation of Nickel Oxide Nanocuboids in Ferromagnetic LaNiMnO.

The control of the spontaneous formation of nanostructures at the surface of thin films is of strong interest in many different fields, from catalysts to microelectronics, because surface and interfacial properties may be substantially enhanced. Here, we analyze the formation of nickel oxide nanocuboids on top of LaNiMnO double perovskite ferromagnetic thin films, epitaxially grown on SrTiO (001) substrates by radio-frequency (RF) magnetron sputtering. We show that, by annealing the films at high temperature under high oxygen partial pressure, the spontaneous segregation of nanocuboids is enhanced.

Aqueous Chemical Solution Deposition of Functional Double Perovskite Epitaxial Thin Films.

Double perovskite structure (A BB'O ) oxides exhibit a breadth of multifunctional properties with a huge potential range of applications in fields as diverse as spintronics, magneto-optic devices, or catalysis, and most of these applications require the use of thin films and heterostructures. Chemical solution deposition techniques are appearing as a very promising methodology to achieve epitaxial oxide thin films combining high performance with high throughput and low cost. In addition, the physical properties of these materials are strongly dependent on the ordered arrangement of cations in the double perovskite structure.

Spontaneous in-flight assembly of magnetic nanoparticles into macroscopic chains.

Knowing the interactions controlling aggregation processes in magnetic nanoparticles is of strong interest in preventing or promoting nanoparticles' aggregation at wish for different applications. Dipolar magnetic interactions, proportional to the particle volume, are identified as the key driving force behind the formation of macroscopic aggregates for particle sizes above about 20 nm. However, aggregates' shape and size are also strongly influenced by topological ordering.

Nanoscale mechanical control of surface electrical properties of manganite films with magnetic nanoparticles.

Mechanical control of electrical properties in complex heterostructures, consisting of magnetic FeO nanoparticles on top of manganite films, is achieved using atomic force microscope (AFM) based methods. Under applied pressure of the AFM tip, drop of the electrical conductivity is observed inducing an electrically insulating state upon a critical normal load. Current and surface potential maps suggest that the switching process is mainly governed by the flexoelectric field induced at the sample surface.

Formation mechanism of glyoxal-DNA adduct, a DNA cross-link precursor.

DNA nucleobases undergo non-enzymatic glycation to nucleobase adducts which can play important roles in vivo. In this work, we conducted a comprehensive experimental and theoretical kinetic study of the mechanisms of formation of glyoxal-guanine adducts over a wide pH range in order to elucidate the molecular basis for the glycation process. Also, we performed molecular dynamics simulations to investigate how open or cyclic glyoxal-guanine adducts can cause structural changes in an oligonucleotide model.

Self-Arranged Misfit Dislocation Network Formation upon Strain Release in La0.7Sr0.3MnO3/LaAlO3(100) Epitaxial Films under Compressive Strain.

Lattice-mismatched epitaxial films of La0.7Sr0.3MnO3 (LSMO) on LaAlO3 (001) substrates develop a crossed pattern of misfit dislocations above a critical thickness of 2.

Macroscopic evidence of nanoscale resistive switching in La2/3Sr1/3MnO3 micro-fabricated bridges.

In this work we report on a combined macro, micro and nanoscale investigation where electronic transport properties through La⅔Sr⅓MnO3 (LSMO) microfabricated bridges, in which nano-sized resistive states are induced by using a conducting scanning probe microscope (C-SPM), are analyzed. The strategy intentionally avoids the standard capacitor-like geometry, thus allowing the study of the electronic transport properties of the locally modified region, and approaches the integration of functional oxides in low dimensional devices while providing macroscopic evidence of nanoscale resistive switching (RS). The metallic and ferromagnetic LSMO is locally modified from its low resistance state (LRS) to a high resistance state (HRS) when a bias voltage is applied on its surface through the conducting tip, which acts as a mobile electrode.

Laparoscopic adrenalectomy Initial experience of 57 cases.

Aim: Analyse the results after 8 years of experience in the laparoscopic treatment of adrenal surgical pathology.

Material Of Study: This is a descriptive retrospective observational study. We analysed the following variables: sex, age, preoperative diagnosis, lesion size (cm) and laterality, operative time series (minutes), conversion to open surgery (%), postoperative complications, average length of hospital stay (days) and the results of pathological anatomy.

Competing misfit relaxation mechanisms in epitaxial correlated oxides.

Strain engineering of functional properties in epitaxial thin films of strongly correlated oxides exhibiting octahedral-framework structures is hindered by the lack of adequate misfit relaxation models. Here we present unreported experimental evidence of a four-stage hierarchical development of octahedral-framework perturbations resulting from a progressive imbalance between electronic, elastic, and octahedral tilting energies in La(0.7)Sr(0.

Nanoscale strain-induced pair suppression as a vortex-pinning mechanism in high-temperature superconductors.

Boosting large-scale superconductor applications require nanostructured conductors with artificial pinning centres immobilizing quantized vortices at high temperature and magnetic fields. Here we demonstrate a highly effective mechanism of artificial pinning centres in solution-derived high-temperature superconductor nanocomposites through generation of nanostrained regions where Cooper pair formation is suppressed. The nanostrained regions identified from transmission electron microscopy devise a very high concentration of partial dislocations associated with intergrowths generated between the randomly oriented nanodots and the epitaxial YBa(2)Cu(3)O(7) matrix.

Chemical solution approaches to YBa2Cu3O7_delta-Au nanocomposite superconducting thin films.

We explore the feasibility of preparing YBa2CU3O7-Au (YBCO-Au) nanocomposite thin films by chemical solution deposition (CSD). Two approaches were used: (i) A standard in-situ methodology where Au metallorganic salts are added into the precursor solution of YBCO trifluoroacetate (TFA) salts and (ii) a novel approach where stable colloidal solutions of preformed gold nanoparticles (5-15 nm) were homogeneously mixed with TFA-YBCO solutions. A detailed analysis of the microstructure of the films showed that in both cases, there is a strong tendency of gold nanoparticles to migrate to the film surface.

Strong isotropic flux pinning in solution-derived YBa2Cu3O7-x nanocomposite superconductor films.

Power applications of superconductors will be tremendously boosted if an effective method for magnetic flux immobilization is discovered. Here, we report the most efficient vortex-pinning mechanism reported so far which, in addition, is based on a low-cost chemical solution deposition technique. A dense array of defects in the superconducting matrix is induced in YBa(2)Cu(3)O(7-x)-BaZrO(3) nanocomposites where BaZrO(3) nanodots are randomly oriented.

Interplay of self-doping and disorder in epitaxial Bi2Sr2Ca(n-1)Cu(n)O(2n+4+x) (n = 1,2) thin films under heavy-Ion irradiation.

We propose a novel mechanism for the modification of T(c) in Bi(2)Sr(2)Ca(n-1)Cu(n)O(2n+4+x) epitaxial thin films (2212 and 2201) under energetic heavy-ion irradiation. By irradiating films with various oxygen content, we show from the temperature dependence of the resistance that irradiation always produces a doping effect superimposed on the damage caused to the sample. The effect is larger in 2201 than in 2212 thin films.