A5073042290- Electronic and Structural Properties of Oxides
- Magnetic and transport properties of perovskites and related materials
- Multiferroics and related materials
- Semiconductor materials and devices
- Advanced Condensed Matter Physics
- Ferroelectric and Piezoelectric Materials
- Advanced X-ray and CT Imaging
- Physics of Superconductivity and Magnetism
- ZnO doping and properties
- Ferroelectric and Negative Capacitance Devices
- Iron-based superconductors research
- Ga2O3 and related materials
- Acoustic Wave Resonator Technologies
- Magnetic properties of thin films
- Surface Roughness and Optical Measurements
- Electron and X-Ray Spectroscopy Techniques
- Atomic and Subatomic Physics Research
- Metal and Thin Film Mechanics
- Transition Metal Oxide Nanomaterials
- Quasicrystal Structures and Properties
- Advancements in Solid Oxide Fuel Cells
- Rare-earth and actinide compounds
- Surface Chemistry and Catalysis
- Corporate Taxation and Avoidance
- Glass properties and applications
Centre National de la Recherche Scientifique
2012-2024
Institut Jean Lamour
2015-2024
Université de Lorraine
2016-2024
John Wiley & Sons (United States)
2018
Interface (United Kingdom)
2018
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2017
Université Paris-Saclay
2016-2017
CEA Paris-Saclay
2017
Normandie Université
2017
École Nationale Supérieure d'Ingénieurs de Caen
2017
We use angle resolved photoemission spectroscopy to study the momentum dependence of superconducting gap in NdFeAsO0.9F0.1 single crystals. find that Gamma hole pocket is fully gapped below transition temperature. The value 15+/-1.5 meV and its anisotropy around smaller than 20% this value-consistent with an isotropic or anisotropic s-wave symmetry order parameter. This a significant departure from situation cuprates, pointing possibility superconductivity iron arsenic based system arises...
Using a low-temperature conductive-tip atomic force microscope in cross-section geometry we have characterized the local transport properties of metallic electron gas that forms at interface between LaAlO3 and SrTiO3. At low temperature, find carriers do not spread away from but are confined within approximately 10 nm, just like room temperature. Simulations taking into account both large temperature electric-field dependence permittivity SrTiO3 predict confinement over few nm for sheet...
With infrared ellipsometry and transport measurements we investigated the electrons at interface between LaAlO3 SrTiO3. We obtained a sheet carrier density of Ns~5-9x 10E13 cm^-2, an effective mass m*~3m_e, strongly frequency dependent mobility. The latter are similar as in bulk SrTi1-xNbxO3 therefore suggestive polaronic correlations confined carriers. also determined vertical profile which has asymmetric shape with rapid initial decay over first 2 nm pronounced tail that extends to about 11 nm.
We study, using angle-resolved photoemission spectroscopy, the two-dimensional electron gas (2DEG) at surface of KTaO${}_{3}$ (KTO), a wide-gap insulator with strong spin-orbit coupling (SOC). find that this 2DEG is genuinely different physical state respect to bulk: orbital symmetries its subbands are entirely reconstructed and their masses renormalized. This occurs because values SOC, Fermi energy, subband splittings become comparable in 2DEG. Additionally, we identify an $F$-center-like...
Organic multiferroic tunnel junctions based on La0.6Sr0.4MnO3/poly(vinylidene fluoride) (PVDF)/Co structures are fabricated. The tunneling magneto-resistance sign can be changed by electrically switching the ferroelectric polarization of PVDF barrier. It is demonstrated that spin-polarization PVDF/Co spinterface actively controlled tuning PVDF. This study opens new functionality in controlling injection spin into organic materials via As a service to our authors and readers, this journal...
Transition metal oxides having a perovskite structure form wide and technologically important class of compounds. In these systems, ferroelectric, ferromagnetic, ferroelastic, or even orbital charge orderings can develop eventually coexist. These be tuned by external electric, magnetic, stress field, the cross-couplings between them enable multifunctional properties, such as piezoelectricity, magneto-electricity, magneto-elasticity. Recently, it has been proposed that additional to typical...
SrTiO 3 becomes a high-mobility metallic conductor when doped with oxygen vacancies at low concentrations (≥1016 cm−3). We show that the vacancy concentration in SrTiO3 single crystal substrates could be controllably tuned by changing thickness of oxide films (deposited pulsed laser deposition high temperature and pressure). The obtained variation carrier density strongly influences transport properties. quantitative analysis experimental results leads toward new accurate strategies for...
Using a combination of advanced characterization tools (positron annihilation spectroscopy, conductive-tip atomic force microscopy, and high-field magnetotransport), we have studied the extension, origin properties high mobility electron gas (HMEG) generated by etching SrTiO3 surfaces with Ar+ ions. Contrary to previous assumptions, show that this HMEG is not confined nanometric thickness but extends few micrometer from surface. We discuss unanticipated large spatial extension in terms...
We present a study of adsorbate screening surface charge in microscopic ferroelectric domains sol–gel grown PbZr0.2Ti0.8O3 thin film. Low-energy and photoemission electron microscopies were employed to characterize the temperature dependence polarization written by atomic force microscopy. role charged adsorbates polarization-bound charges. demonstrate that full-field microscopy is suitable for determination system properties such as Curie temperature.
A series of 100 nm LaVO3 thin films have been synthesized on (001)-oriented SrTiO3 substrates using the pulsed laser deposition technique, and effects growth temperature are analyzed.Transport properties reveal a large electronic mobility non-linear Hall effect at low temperature.In addition, cross-over from semiconducting state high-temperature to metallic low-temperature is observed, with clear enhancement character as increases.Optical absorption measurements combined two-bands analysis...
We have carried out positron-annihilation spectroscopy to characterize the spatial distribution and nature of vacancy defects in insulating as-received as well reduced ${\text{SrTiO}}_{3}$ substrates exhibiting high-mobility conduction. The were either by ion etching substrate surfaces or doping with vacancies during thin-film deposition at low pressure high temperature. show that Ti are native homogeneously distributed substrates. In contrast, dominant same both etched crystals film growth,...
The interplay between charge, spin, orbital and lattice degrees of freedom in transition metal oxides has motivated extensive research aiming to understand the coupling phenomena these multifunctional materials. Among them, rare earth vanadates are Mott insulators characterized by spin orderings strongly influenced distortions. Using epitaxial strain as a means tailor unit cell deformation, we report here on first thin films PrVO3 grown (001)-oriented SrTiO3 substrate pulsed laser...
Transition-metal oxides with an ABO$_3$ perovskite structure exhibit strongly entangled structural and electronic degrees of freedom thus, one expects to unveil exotic phases properties by acting on the lattice through various external stimuli. Using Jahn-Teller active praseodymium vanadate Pr$^{3+}$V$^{3+}$O$_3$ compound as a model system, we show that PrVO$_3$ N\'eel temperature T$_N$ can be raised 40 K respect bulk when grown thin films. advanced experimental techniques, this enhancement...
While structure refinement is routinely achieved for simple bulk materials, the accurate structural determination still poses challenges thin films due on one hand to small amount of material deposited thicker substrate and, other hand, intricate epitaxial relationships that substantially complicate standard X-ray diffraction analysis. Using a combined approach, we analyze crystal LaVO$_3$ grown (100)-oriented SrTiO$_3$. Transmission electron microscopy study reveals are epitaxially...
Combining multiple degrees of freedom in strongly correlated materials such as transition-metal oxides would lead to fascinating magnetic and magnetocaloric features. Herein, the strain effects are used markedly tailor properties PrVO3 thin films. The selection an appropriate thickness substrate enables us dramatically decrease coercive field from 2.4 T previously observed sintered PVO3 bulk 0.05 for compressive films making compound a nearly soft magnet. This is associated with marked...
It is well known that transport in lightly $n$-doped ${\mathrm{SrTiO}}_{3}$ involves light and heavy electron bands. We have found upon application of moderate quasi-isotropic pressures, the relative positions these subbands are changed by a few meV and, eventually, band inversion occurs at $\ensuremath{\sim}1\text{ }\text{ }\mathrm{kbar}$. Such effects are, however, suppressed closely related ${\mathrm{KTaO}}_{3}$ perovskite. show extremely subtle electronic reconfiguration triggered...
Functional oxides and phenomena such as a 2D electron gas (2DEG) at oxide interfaces represent potential technological breakthroughs for post-CMOS electronics. Non-invasive techniques are required to study the surface chemistry electronic structure, underlying their often unique electrical properties. The sensitivity of photoemission microscopy structure makes it an invaluable tool probing near region microscopic regions domains functional materials. We present results demonstrating room...
The formation of two-dimensional oxide dodecagonal quasicrystals as well related complex approximant phases was recently reported in thin films derived from BaTiO3 or SrTiO3 perovskites deposited on (111)-oriented Pt single crystals. Here, we use an all-thin-film approach which the crystal is replaced by a 10 nm thick Pt(111) buffer layer grown molecular beam epitaxy Al2O3(0001) substrate. An ultra-thin film subsequently pulsed laser deposition. stacking and structure are fully characterized...
In recent years, multifunctional materials have attracted increasing interest for magnetic memories and energy harvesting applications. Magnetic insulating are of special this purpose, since they allow the design more efficient devices due to lower Joule heat losses. context, Ga$_{0.6}$Fe$_{1.4}$O$_3$ (GFO) is a good candidate spintronics applications, it can exhibit multiferroicity presents spin Hall magnetoresistance similar one observed in yttrium iron garnet (YIG)/Pt bilayer. Here, we...
The spontaneous ordering of a two-dimensional (2D) SrTiO3-derived film supported on Pt(111)/Al2O3(0001) is investigated by scanning tunneling microscopy. After annealing under ultrahigh vacuum, 2D reduced wetting layer formed where oxide quasicrystal approximants are observed. Upon increasing the number preparation cycles, Sr content in decreases. structure then evolves into Ti2O3 honeycomb (HC) lattice partially decorated adatoms. latter localized hollow sites network, with several complex...
Spintronics is showing promising results in the search for new materials and effects to reduce energy consumption information technology. Among these materials, ferrimagnets are of special interest, since they can produce large spin currents that trigger magnetization dynamics adjacent layers or even their own magnetization. Here, we present a study generation current by GdFeCo GdFeCo/Cu/NiFe trilayer where FeCo sublattice dominant at room temperature. Magnetic properties such as saturation...
In cobaltite, the spin states transitions of Co3+/4+ ions govern magnetic and electronic conduction properties. These are strain-sensitive can be varied using external parameters, including temperature, hydrostatic pressure, or chemical stresses through ionic substitutions. this work, temperature dependent Raman spectroscopy X-ray diffraction, epitaxial strain effects on both structural vibrational properties La0.7 Ba0.3 CoO3 (LBCO) cobaltite thin films investigated. All active phonon modes...