A5042440046- Ferroelectric and Piezoelectric Materials
- Multiferroics and related materials
- Acoustic Wave Resonator Technologies
- Electronic and Structural Properties of Oxides
- Nonlocal and gradient elasticity in micro/nano structures
- Force Microscopy Techniques and Applications
- Magnetic and transport properties of perovskites and related materials
- Magnetic confinement fusion research
- Microwave Dielectric Ceramics Synthesis
- Advanced Sensor and Energy Harvesting Materials
- Advanced Condensed Matter Physics
- Solid-state spectroscopy and crystallography
- Semiconductor materials and devices
- Transition Metal Oxide Nanomaterials
- Dielectric properties of ceramics
- Adhesion, Friction, and Surface Interactions
- Perovskite Materials and Applications
- Ga2O3 and related materials
- Mechanical and Optical Resonators
- Ferroelectric and Negative Capacitance Devices
- Ionosphere and magnetosphere dynamics
- Advanced Memory and Neural Computing
- Ultrasonics and Acoustic Wave Propagation
- Dielectric materials and actuators
- ZnO doping and properties
Institució Catalana de Recerca i Estudis Avançats
2016-2025
Institut Català de Nanociència i Nanotecnologia
2016-2025
Universitat Autònoma de Barcelona
2013-2024
Institut de Nanociència i Nanotecnologia de la Universitat de Barcelona
2024
Consejo Superior de Investigaciones Científicas
2010-2022
University of Groningen
2005-2020
Czech Academy of Sciences
2020
Czech Academy of Sciences, Institute of Physics
2020
University of Illinois Urbana-Champaign
2020
Centre d’Élaboration de Matériaux et d’Études Structurales
2020
Abstract BiFeO 3 is perhaps the only material that both magnetic and a strong ferroelectric at room temperature. As result, it has had an impact on field of multiferroics comparable to yttrium barium copper oxide (YBCO) superconductors, with hundreds publications devoted in past few years. In this Review, we try summarize basic physics unresolved aspects (which are still being discovered several new phase transitions reported months) device applications, which center spintronics memory...
Domains in ferroelectrics were considered to be well understood by the middle of last century: They generally rectilinear, and their walls Ising-like. Their simplicity stood stark contrast more complex Bloch or N\'eel magnets. Only within past decade with introduction atomic-resolution studies via transmission electron microscopy, holography, atomic force microscopy polarization sensitivity has real complexity been revealed. Additional phenomena appear recent studies, especially...
Flexoelectricity—the coupling between polarization and strain gradients—is a universal effect allowed by symmetry in all materials. Following its discovery several decades ago, studies of flexoelectricity solids have been scarce due to the seemingly small magnitude this bulk samples. The development nanoscale technologies, however, has renewed interest flexoelectricity, as large gradients often present at can lead strong flexoelectric effects. Here we review fundamentals solids, discuss...
The existence of a magnetodielectric (magnetocapacitance) effect is often used as test for multiferroic behavior in new material systems. However, strong effects can also be achieved through combination magnetoresistance and the Maxwell-Wagner effect, unrelated to coupling. fact that this resistive magnetocapacitance does not require materials may advantageous some practical applications. Conversely, it implies per se sufficient establish
Changing Polarization with Applied Stress The direction of electric polarization in ferroelectric materials can be switched an applied field, but mechanical stresses also couple to the polarization, forming basis for piezoelectric effects. In principle, it should possible change a material mechanically through stress gradients. Lu et al. (p. 59 ; see Perspective by Gregg ) demonstrate such switching nanoscale-sized regions created induced atomic force microscope. substrates are...
We report on extensive experimental studies thin film, single crystal, and ceramics of multiferroic bismuth ferrite $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}$ using differential thermal analysis, high-temperature polarized light microscopy, Raman spectroscopy, x-ray diffraction, dc conductivity, optical absorption reflectivity, domain imaging, show that epitaxial (001) films are clearly monoclinic at room temperature, in agreement with recent synchrotron but disagreement all other earlier...
Piezoelectricity is inherent only in noncentrosymmetric materials, but a piezoelectric response can also be obtained centrosymmetric crystals if subjected to inhomogeneous deformation. This phenomenon, known as flexoelectricity, significantly affect the functional properties of insulators, particularly thin films high permittivity materials. We have measured strain-gradient-induced polarization single paraelectric SrTiO3 function temperature and orientation down below 105 K phase transition....
Abstract Perovskite nickelates (RNiO3, where R is rare earth or a heavy metal such as Tl Bi) display sharp metal–insulator transitions, unusual magnetic order, charge order and, perhaps, orbital order. Furthermore, there are strong reasons to believe that some of them may be magnetoelectric multiferroics. In this article the author reviews recent research perovskite nickelates, highlighting important role thin film has contributed our understanding their properties. A special emphasis placed...
Domains in ferroelectric films are usually smooth, stripelike, very thin compared with magnetic ones, and satisfy the Landau-Lifshitz-Kittel scaling law (width proportional to square root of film thickness). However, domains multiferroic BiFeO3 have irregular domain walls characterized by a roughness exponent 0.5-0.6 in-plane fractal Hausdorff dimension H||=1.4+/-0.1, size scales an 0.59+/-0.08 rather than 1/2. The significantly larger those other ferroelectrics same thickness, closer...
Reversible electric-field control of the metal-insulator transition in rare earth nickelate compound NdNiO3 is demonstrated. Using electric double layer technique, giant modulations conductance as well large shifts temperature are obtained.
We have measured the flexophotovoltaic effect of single crystals halide perovskites MAPbBr3 and MAPbI3, as well benchmark oxide perovskite SrTiO3. For perovskites, is found to be orders magnitude larger than for SrTiO3, indeed large enough induce photovoltages bigger band gap. Moreover, we find that in MAPbI3 additional a native bulk photovoltaic response switchable ferroelectric-like. The results suggest strain gradient engineering can powerful tool modify output even already...
X-ray analysis of ferroelectric thin layers Ba1/2Sr1/2TiO3 with different thickness reveals the presence internal strain gradients across film and allows us to propose a functional form for profile. We use this calculate direct influence gradient, through flexoelectric coupling, on degradation properties films decreasing thickness, in excellent agreement observed behaviour. This work highlights link between relaxation epitaxial films, shows pressing need avoid order obtain ferroelectrics...
Recent experimental measurements of large flexoelectric coefficients in ferroelectric ceramics suggest that strain gradients can affect the polarization and permittivity behaviour inhomogeneously strained ferroelectrics. Here we present a phenomenological model effect flexoelectricity on dielectric constant, polarization, Curie temperature (TC), maximum constant (Tm) onset reversible (Tferro) for thin films subject to substrate-induced epitaxial strains are allowed relax with thickness,...
A Maxwell–Wagner series capacitor model is proposed to explain anomalous dielectric properties of ferroelectric superlattices. The results the show that a superlattice consisting normal layers separated by low-resistivity interfacial regions can account for most experimental reported date, namely: enhancement certain stacking periodicities, giant permittivities, and temperature migration maxima as function frequency. predictions are discussed compared our own from thin film capacitors made...
Almost free-standing single crystal mesoscale and nanoscale dots of ferroelectric BaTiO3 have been made by direct focused ion beam patterning bulk material. The domain structures which appear in these dots, after cooling through the Curie temperature, were observed to form into quadrants, with each quadrant consisting fine 90° stripe domains. reason that rather complex configurations is uncertain, but we consider discuss three possibilities for their genesis: first, features initially...
We present ab initio calculations of the longitudinal flexoelectricity for BaTiO(3) and SrTiO(3) using a direct approach. The calculated value agrees with recently reported measurements. For BaTiO(3), however, theoretical values are smaller than measured ones; possible reasons discrepancy discussed.
Abstract Bones generate electricity under pressure, and this electromechanical behavior is thought to be essential for bone's self‐repair remodeling properties. The origin of response attributed the piezoelectricity collagen, which main structural protein bones. In theory, however, any material can also voltages in strain gradients, thanks property known as flexoelectricity. work, flexoelectricity bone pure mineral (hydroxyapatite) are measured found same order magnitude; quantitative...
Domain walls in multiferroics can exhibit intriguing behaviors that are significantly different from the bulk of material. We investigate strong magnetoresistance domain model multiferroic BiFeO3 by probing ordered arrays 109° with temperature- and magnetic-field-dependent transport. observe temperature-dependent variations transport mechanism magnetoresistances as large 60%. These results suggest locally breaking symmetry a material, such at structural interfaces, one induce emergent...
We calculate the exact analytical solution to domain wall properties in a generic multiferroic system with two order parameters that are coupled biquadratically. This is then adapted case of magnetoelectric material such as ${\text{BiFeO}}_{3}$, view examine critically whether walls can account for enhancement magnetization reported thin films this material, correlation between increasing and volume fraction become thinner. The present analysis be generalized describe class devices based on...
Abstract Converse flexoelectricity is a mechanical stress induced by an electric polarization gradient. It can appear in any material, irrespective of symmetry, whenever there inhomogeneous field distribution. This situation invariably happens piezoresponse force microscopy (PFM), which technique whereby voltage delivered to the tip atomic microscope order stimulate and probe piezoelectricity at nanoscale. While PFM premier for studying ferroelectricity nanoscale, here we show, theoretically...