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.

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.

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.

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.

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.

Controlling exchange bias in Co-CoOx nanoparticles by oxygen content.

We report on the occurrence of exchange bias on laser-ablated granular thin films composed of Co nanoparticles embedded in an amorphous zirconia matrix. The deposition method allows one to control the degree of oxidation of the Co particles by tuning the oxygen pressure at the vacuum chamber (from 2 x 10(-5) to 10(-1) mbar). The nature of the nanoparticles embedded in the nonmagnetic matrix is monitored from metallic, ferromagnetic (FM) Co to antiferromagnetic (AFM) CoO(x), with a FM/AFM intermediate regime for which the percentage of the AFM phase can be increased at the expense of the FM phase, leading to the occurrence of exchange bias in particles of about 2 nm in size.

Strain-driven self-assembled network of antidots in complex oxide thin films.

Structural strain due to lattice mismatch is used to promote the formation of a self-assembled network of antidots in highly epitaxial La(2/3)Sr(1/3)MnO(3) thin films grown on (001) oriented SrTiO(3) substrates by radiofrequency magnetron sputtering. Size, depth, and separation between antidots can be controlled by changing deposition parameters and the miscut angle of the substrate. This morphology exhibits a remarkable magnetic anisotropy and offers unique opportunities for versatile nanostencils for the preparation of nano-object networks that can be of major relevance for the fabrication of oxide-based magnetic and magnetoelectronic devices.

Particle growth mechanisms in Ag-ZrO(2) and Au-ZrO(2) granular films obtained by pulsed laser deposition.

Thin films consisting of Ag and Au nanoparticles embedded in amorphous ZrO(2) matrix were grown by pulsed laser deposition in a wide range of metal volume concentrations in the dielectric regime (0.08 View Article and Find Full Text PDF