A5105267298- Multiferroics and related materials
- Ferroelectric and Piezoelectric Materials
- Magnetic and transport properties of perovskites and related materials
- Magnetic properties of thin films
- Electronic and Structural Properties of Oxides
- Advanced Memory and Neural Computing
- Molecular Junctions and Nanostructures
- Quantum and electron transport phenomena
- Advanced Condensed Matter Physics
- Semiconductor materials and devices
- Physics of Superconductivity and Magnetism
- Ferroelectric and Negative Capacitance Devices
- Force Microscopy Techniques and Applications
- Surface and Thin Film Phenomena
- Dielectric properties of ceramics
- Magnetic Properties and Synthesis of Ferrites
- Silicon Nanostructures and Photoluminescence
- Organic Light-Emitting Diodes Research
- Magneto-Optical Properties and Applications
- Laser-Ablation Synthesis of Nanoparticles
- Magnetic Field Sensors Techniques
- Characterization and Applications of Magnetic Nanoparticles
- Electrostatics and Colloid Interactions
- Diamond and Carbon-based Materials Research
- Porphyrin and Phthalocyanine Chemistry
Centre National de la Recherche Scientifique
2011-2024
Université Paris-Saclay
2016-2024
Thales (France)
2024
Laboratoire Matériaux et Phénomènes Quantiques
2023
Laboratoire Albert Fert
2010-2019
Université Paris-Sud
2010-2019
École Polytechnique
2009-2016
Université d'Évry Val-d'Essonne
2002-2013
Université Paris Cité
2009-2010
UCLouvain
2003
A current drawback of spintronics is the large power that usually required for magnetic writing, in contrast with nanoelectronics, which relies on "zero-current," gate-controlled operations. Efforts have been made to control spin-relaxation rate, Curie temperature, or anisotropy a gate voltage, but these effects are small and volatile. We used ferroelectric tunnel junctions ferromagnetic electrodes demonstrate local, large, nonvolatile carrier spin polarization by electrically switching...
Ultrathin layers of the versatile spinel oxide NiFe2O4 can be conductive or insulating depending on growth conditions. Conductive (NFO) electrodes are inserted into conventional magnetic tunnel junctions containing La2/3Sr1/3MnO3/SrTiO3 (LMSO/STO) bilayers, and ferrimagnetic used as barriers to define a spin filter (see figure). The ability such heterostructures highly spin-polarize electrons injected from non-magnetic electrode is demonstrated.
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...
Ferroelectric tunnel junctions enable a nondestructive readout of the ferroelectric state via change resistance induced by switching polarization. We fabricated submicrometer solid-state based on recently discovered polymorph BiFeO3 with giant axial ratio ("T-phase"). Applying voltage pulses to leads highest changes (OFF/ON >10,000) ever reported junctions. Along good retention properties, this effect reinforces interest in nonvolatile memories also show that scale nucleation and growth...
We have explored the influence of deposition pressure and temperature on growth BiFeO3 thin films by pulsed laser onto (001)-oriented SrTiO3 substrates. Single-phase are obtained in a region close to 10−2mbar 580°C. In nonoptimal conditions, x-ray diffraction reveals presence Fe oxides or Bi2O3. address these parasitic phases magnetic electrical properties show that with Fe2O3 systematically exhibit ferromagnetic behavior, while single-phase low bulklike moment. Conductive-tip atomic force...
We have combined neutron scattering and piezoresponse force microscopy to show that the exchange field in CoFeB/BiFeO_{3} heterostructures scales with inverse of ferroelectric antiferromagnetic domain size BiFeO3 films, as expected from Malozemoff's model bias extended multiferroics. Accordingly, polarized reflectometry reveals presence uncompensated spins film at interface CoFeB. In view these results, we discuss possible strategies switch magnetization a ferromagnet by an electric using BiFeO3.
Single phase (001)-oriented ${\mathrm{BiFeO}}_{3}$ (BFO) thin films grown by pulsed laser deposition can only be obtained in a narrow window of pressure and temperature have low magnetic moment. Out the stability Fe- or Bi-rich impurity phases form, which has strong impact on physical structural properties films, even for concentrations hardly detectable standard x-ray diffraction measurements. By using more sensitive tools such as absorption spectroscopy circular dichroism performing...
We report on experiments of spin filtering through ultrathin single-crystal layers the insulating and ferromagnetic oxide $\mathrm{Bi}\mathrm{Mn}{\mathrm{O}}_{3}$ (BMO). The polarization electrons tunneling from a gold electrode BMO is analyzed with counterelectrode half-metallic ${\mathrm{La}}_{2∕3}{\mathrm{Sr}}_{1∕3}\mathrm{Mn}{\mathrm{O}}_{3}$ (LSMO). At $3\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ we find 50% change tunnel resistances according to whether magnetizations LSMO are parallel or...
We report experiments of spin-filtering through ultrathin insulating layers the high Curie temperature ferrimagnetic oxide NiFe2O4 (NFO). The efficiency electrons tunneling from a gold electrode NFO is analyzed with counter-electrode La2∕3Sr1∕3MnO3 (LSMO). measure tunnel magnetoresistance 40%–50% when configuration magnetizations and LSMO goes parallel to antiparallel. This value corresponds up 22% by barrier. discuss sign dependence spin-filter effect argue that our results show potential...
Magnetoelectric multiferroics are attractive materials for the development of low-power electrically controlled spintronic devices. Here we report optimization exchange bias as well giant magnetoresistance effect (GMR) spin valves deposited on top BiFeO(3)-based heterostructures. We show that can be through a change in relative proportion 109° domain walls and propose solutions toward reversible process.
We report the influence of epitaxial strain on multiferroic phase transitions BiFeO3 films. Using advanced characterization techniques and calculations we show that while magnetic Néel temperature hardly varies, ferroelectric Curie TC decreases dramatically with strain. This is in contrast behavior standard ferroelectrics where enhances polar cation shifts thus TC. argue this caused by an interplay oxygen tilting instabilities can drive both close together to yield increased magnetoelectric...
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...
In tunnel junctions with ferroelectric barriers, switching the polarization direction modifies electrostatic potential profile and associated average barrier height. This results in strong changes of transmission resistance. The information readout (FTJs) is thus resistive non-destructive, which an advantage compared to case conventional memories (FeRAMs). Initially, endurance limitation (i.e., fatigue) was main factor hampering industrialization FeRAMs. Systematic investigations dynamics...
We report on the fabrication and spin dependent tunneling studies of magnetic tunnel junctions (MTJs) grown flexible organic substrates. observe comparable magnetoresistance (TMR) effects in standard Co/Al2O3/Co MTJs either buffered polyester based substrates or silicon wafers. Moreover we show that after twisting bending TMR magnitude is maintained which indicates properties are preserved. This demonstrates spintronics devices compatible with embodied electronics.
Using heterostructures that combine a large-polarization ferroelectric (${\mathrm{BiFeO}}_{3}$) and high-temperature superconductor (${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$), we demonstrate the modulation of superconducting condensate at nanoscale via field effects. Through this mechanism, pattern normal regions mimics domain structure can be created in superconductor. This yields an energy landscape for magnetic flux quanta and, turn, couples...
In multiferroic BiFeO(3) thin films grown on highly mismatched LaAlO(3) substrates, we reveal the coexistence of two differently distorted polymorphs that leads to striking features in temperature dependence structural and properties. Notably, phase quasiconcomitantly presents an abrupt change, transforms from a standard nonconventional ferroelectric, transitions antiferromagnetic paramagnetic at 360±20 K. These coupled ferroic just above room hold promises giant piezoelectric,...