Hematite (α-Fe2O3) can be considered as one of the top candidates to act photoanode in framework clean hydrogen production through solar water splitting. The O:Fe ratio, that this material plays a crucial role definition its photoelectrochemical properties, has been investigated detail. For purpose, we examined thermal magnetite oxidation and hematite reduction two possible routes produce semiconducting iron oxides layers with controlled stoichiometry. We report on properties single...

Undoped and Ti-doped (2 at. %) epitaxial hematite thin films, in the thickness range 5–50 nm, were grown by atomic oxygen assisted molecular beam epitaxy (AO-MBE) on Pt(111) substrates framework of hydrogen harvesting from sunlight-induced water splitting. Such single crystalline samples are suitable model systems to study doping effects photoelectrochemical properties; we demonstrate that they also allow disentangling intrinsic transport properties mingled overall due usually unknown...

We have found evidence for a strong magnetoelectric (ME) coupling at room temperature between polycrystalline Co layers ($5\ensuremath{-}40$ nm) and single-crystalline (001)-oriented BaTiO${}_{3}$ ($15\ensuremath{-}17$ nm). took advantage of the quasi-single polarization orientation, perpendicular to film plane, ferroelectric domains in tetragonal phase. Using ferromagnetic resonance spectroscopy with magnetization aligned either parallel or antiparallel polarization, we assessed anisotropy...

The growth, crystal and electronic structures, photo-electrochemical properties of undoped Ti doped hematite epitaxial films were studied. We evidence that Ti4+ substitutes Fe3+ in the lattice inducing a slight modification oxygen octahedron. doping is shown to induce shift valence band toward higher binding energy due movement Fermi level conduction band. resulting electrical conductivity appears as possible origin improvement sample.

We demonstrate on prototypical samples containing a ferroelectric layer (BaTiO3/Nb:SrTiO3) that the efficiency of system, used as photoanode, substantially depends polarization state layer. show significant increase photocurrent by factor larger than 2 when BaTiO3 film is downward polarized. explain this finding presence an internal electric field which favors separation photo-generated charges.

In this work the thermal heating of tunnel junctions is investigated doing one-dimensional numerical simulations by solving heat equation. The temperature increase proportional to power density jV, which confirmed transport measurements on patterned μm size junctions. observed was 2.3 K/(mW μm−2) compared a simulation result 0.9 μm−2). Tunneling AFM 4, 5.4, and 6.7 Å barrier half-junctions, show hot spots with current densities up 13 times average value. concentration could explain higher...

In addition to a storage function through the magnetization of nanowires, domain wall propagation can be used trigger magnetic logic functions. Here, we present new way realize pure operation by using nanowires with perpendicular anisotropy. Emphasis is given on generation 'NOT' that based dipolar interaction between two neighbouring wires, which favours creation wall. This concept has been validated several prototypes and results fit well expectations.

Direct evidence for reductive and oxidative surface states coexisting in hematite nanostructures is given by combined STXM PEC measurements. The annealing temperature Ti substitution balance the states, driving activity.

Multiferroic biphase systems with robust ferromagnetic and ferroelectric response at room temperature would be ideally suitable for voltage-controlled nonvolatile memories. Understanding the role of strain charges interfaces is central an accurate control ferroelectricity as well ferromagnetism. In this paper, we probe relationship between ferromagnetic/ferroelectric properties in layered CoFe2O4/BaTiO3 (CFO/BTO) model system. For purpose, ultrathin epitaxial bilayers, ranging from highly...

This paper reports on the influence of ion irradiation magnetic properties Co∕Ni multilayers with perpendicular anisotropy (PMA). material is a very promising candidate for ultrahigh density spintronic applications since it exhibits high polarization and low damping parameters. We show that PMA can be tailored in controlled way by using uniform He+ or focused Ga+ beam.

We studied the growth of epitaxial ferroelectric layers BaTiO3/Pt(001) in framework solar water splitting. The stoichiometry, that is, Ti/Ba ratio, appears as a crucial parameter not only for crystallographic structure but also photocurrent generation when sample is used photoanode. established an electrochemical poling method using modulated potential, without altering to control electric polarization. Importantly, we show photoanode efficiency improved polarization film oriented toward...

We have investigated the growth of BaTiO3 thin films deposited on pure and 1% Nb-doped SrTiO3(001) single crystals using atomic oxygen assisted molecular beam epitaxy dedicated Ba Ti Knudsen cells. Thicknesses up to 30 nm were for various layer compositions. demonstrate 2D epitaxial crystalline layers 10 before additional 3D features appear; lattice parameter relaxation occurs during first few nanometers is completed at ∼10 nm. The presence a oxide rich top that probably favors evidenced...

We report on the Fe doping and comparative Ni-Fe codoping with composition close to $\mathrm{NiF}{\mathrm{e}}_{2}$ of fully oxidized $\mathrm{BaTi}{\mathrm{O}}_{3}$ layers (\ensuremath{\sim}20 nm) elaborated by atomic oxygen plasma assisted molecular beam epitaxy; specifically any role vacancies can be excluded in our films. Additionally classical situ laboratory tools, films were thoroughly characterized synchrotron radiation x-ray diffraction absorption spectroscopy. For purely Fe-doped...

Photocatalysis and photoelectrochemical (PEC) activities not only strongly depend on the chemical formulae of electrode materials, but also local ionic environment that deserves to be addressed in detail for a given compound. Specifically, within framework PEC water splitting, we studied growth, crystal electronic structures, properties thin epitaxial films TiO2 deposited Pt(111), Pt(001), Nb:SrTiO3(001) substrates. We found crystallographic structure is respectively rutile (100), anatase...

Band engineering is employed thoroughly and targets technologically scalable photoanodes for solar water splitting applications. Complex costly recipes are necessary, often average performances. Here, we report simple photoanode growth thermal annealing with effective band results. By comparing Ti-doped hematite annealed under nitrogen to in air, found a strongly enhanced photocurrent of more than 200% the first case. Using electrochemical impedance spectroscopy synchrotron X-ray...

We report a new macroscopic first-field-induced magnetic anisotropy for $\mathrm{Co}/\ensuremath{\alpha}\mathrm{\text{\ensuremath{-}}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}(0001)$ layers, prototypical ferromagnetic-antiferromagnetic interface which the antiferromagnetic film has small in-plane as compared to coupling. demonstrate that effect is due irreversible domain motion in layer, dragged by ferromagnetic Co one. Whereas initial matching lost, manifestations of exchange coupling remain...

We present broadband measurements of the magnetoimpedance polycrystalline La0.7Sr0.3MnO3 films grown on silicon as a function three parameters: (i) frequency (0–1GHz), (ii) temperature (4–275K), and (iii) applied magnetic field (0–6T). In this paper it is evidenced that magnetoresistive effect still exists up to 1GHz. The impedance variation with well modeled considering film equivalent random resistive-capacitive network. Similar behaviors versus are observed in dc high range.

Superconducting a-NbxSi1-x thin films experience a lowering of the Tc until superconductivity disappears through Superconductor-Insulator Transition (SIT). We here present transport measurements on 2D films, close to SIT, for different compositions and thicknesses. investigate in light existing theories, especially one developed by Finkel'stein.