A5034812969- Magnetic and transport properties of perovskites and related materials
- Electronic and Structural Properties of Oxides
- Ferroelectric and Piezoelectric Materials
- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Multiferroics and related materials
- Semiconductor materials and devices
- Acoustic Wave Resonator Technologies
- Magnetic properties of thin films
- Gas Sensing Nanomaterials and Sensors
- Superconductivity in MgB2 and Alloys
- Transition Metal Oxide Nanomaterials
- Theoretical and Computational Physics
- Rare-earth and actinide compounds
- Iron-based superconductors research
- Advanced Memory and Neural Computing
- Advanced MEMS and NEMS Technologies
- Force Microscopy Techniques and Applications
- Magnetic Properties of Alloys
- Catalysis and Oxidation Reactions
- Surface and Thin Film Phenomena
- Ferroelectric and Negative Capacitance Devices
- Superconducting Materials and Applications
- Advanced Materials Characterization Techniques
- Inorganic Chemistry and Materials
University of Geneva
2016-2025
Northwestern University
2023
TU Wien
2022
Institut Català de Nanociència i Nanotecnologia
2022
University of Luxembourg
2020-2021
Luxembourg Institute of Science and Technology
2020-2021
University of Arkansas at Fayetteville
2020
ETH Zurich
2020
Max Planck Institute for the Structure and Dynamics of Matter
2011
Universität Hamburg
2011
At interfaces between complex oxides, electronic systems with unusual properties can be generated. We report on superconductivity in the electron gas formed at interface two insulating dielectric perovskite LaAlO 3 and SrTiO . The behavior of is that a two-dimensional superconductor, confined to thin sheet interface. superconducting transition temperature ≅ 200 millikelvin provides strict upper limit thickness layer 10 nanometers.
Complex transition metal oxides span a wide range of crystalline structures and play host to an incredible variety physical phenomena. High dielectric permittivities, piezo-, pyro-, ferroelectricity are just few the functionalities offered by this class materials, while potential for applications more exotic properties like high temperature superconductivity colossal magnetoresistance is still waiting be fully exploited. With recent advances in deposition techniques, structural quality oxide...
Ferroelectric oxide materials have offered a tantalizing potential for applications since the discovery of ferroelectric perovskites more than 50 years ago. Their switchable electric polarization is ideal use in devices memory storage and integrated microelectronics, but progress has long been hampered by difficulties processing. Recent breakthroughs synthesis complex oxides brought field to an entirely new level, which artificial structures can be realized with atomic-level precision...
The quasi-two-dimensional electron gas found at the LaAlO{3}/SrTiO{3} interface offers exciting new functionalities, such as tunable superconductivity, and has been proposed a nanoelectronics fabrication platform. Here we lay out example of an electronic property arising from interfacial breaking inversion symmetry, namely, large Rashba spin-orbit interaction, whose magnitude can be modulated by application external electric field. By means magnetotransport experiments explore evolution...
Ferroelectric switching and nanoscale domain dynamics were investigated using atomic force microscopy on monocrystalline Pb(Zr(0.2)Ti(0.8))O(3) thin films. Measurements of size versus writing time reveal a two-step growth mechanism, in which initial nucleation is followed by radial wall motion perpendicular to the polarization direction. The electric field dependence velocity demonstrates that ferroelectric films creep process, with critical exponent mu close 1. dimensionality suggests...
We report on the investigation of ferroelectricity in thin tetragonal single-crystalline perovskite films Pb(Zr0.2Ti0.8)O3 grown by off-axis rf magnetron sputtering. The local ferroelectric properties atomically smooth films, with thicknesses ranging from a few unit cells to 800 Å, were measured using combination electric force microscopy and piezoelectric microscopy. time dependence signals reveals stable polarization down 40 Å.
We have artificially varied the coupling between ultrathin ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ layers by interposing insulating planes of ${\mathrm{PrBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ in multilayers and studied consequences decoupling 12-A\r{} unit cells on superconducting properties. find that ${\mathrm{T}}_{\mathrm{c}}$ (midpoint) a 12-A\r{}/12-A\r{} multilayer is 55 K, twice corresponding alloy. decreases linearly with further separation cells,...
Direct, charge-mediated magnetoelectric coupling is demonstrated in a heterogeneous multiferroic that takes advantage of the sensitivity strongly correlated magnetic system to competing electronic ground states. Using magneto-optic Kerr effect magnetometry, we observe large ferroelectric/lanthanum manganite heterostructures, resulting control state by means an applied electric field, as illustrated figure.
Transport in ultrathin films of LaNiO(3) evolves from a metallic to strongly localized character as the film's thickness is reduced and sheet resistance reaches value close h/e(2), quantum two dimensions. In intermediate regime, corrections Drude low-temperature conductivity are observed; they accurately described by weak localization theory. Remarkably, negative magnetoresistance this regime isotropic, which points magnetic scattering associated with proximity system either spin-glass state...
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.
Abstract The metal–insulator transition and the intriguing physical properties of rare-earth perovskite nickelates have attracted considerable attention in recent years. Nonetheless, a complete understanding these materials remains elusive. Here we combine X-ray absorption resonant inelastic scattering (RIXS) spectroscopies to resolve important aspects complex electronic structure nickelates, taking NdNiO 3 thin film as representative example. unusual coexistence bound continuum excitations...
The evolution of tetragonality with thickness has been probed in epitaxial $c$-axis oriented ${\mathrm{P}\mathrm{b}\mathrm{T}\mathrm{i}\mathrm{O}}_{3}$ films thicknesses ranging from 500 down to $24\text{ }\text{ }\AA{}$. High resolution x ray pointed out a systematic decrease the lattice parameter decreasing film below $200\text{ Using first-principles model Hamiltonian approach, is related reduction polarization attributed presence residual unscreened depolarizing field. It shown that...
The polarization field of the ferroelectric oxide lead zirconate titanate [Pb(ZrxTi1-x)O3] was used to tune critical temperature hightemperature superconducting cuprate gadolinium barium copper (GdBa2Cu3O7-x) in a reversible, nonvolatile fashion. For slightly underdoped samples, uniform shift several Kelvin observed, whereas for more an insulating state induced. This transition from behavior does not involve chemical or crystalline modification material.
A scanning probe microscope was used to induce local, nonvolatile field effects in epitaxial, ferroelectric Pb(Zr 0.52 Ti 0.48 )O 3 /SrRuO heterostructures. Field-effected regions with linewidths as small 3500 angstroms were written by locally switching the polarization of layer; electronic density underlying metallic SrRuO layer modified and sheet resistance changed up 300 ohms per square. This procedure is completely reversible allows submicrometer features be directly two dimensions, no...
We report on a study of magnetotransport in ${\mathrm{LaAlO}}_{3}/{\mathrm{SrTiO}}_{3}$ interfaces characterized by mobilities the order several thousands ${\mathrm{cm}}^{2}/\mathrm{V}\text{ }\mathrm{s}$. observe Shubnikov--de Haas oscillations whose period depends only perpendicular component magnetic field. This observation directly indicates formation two-dimensional electron gas originating from quantum confinement at interface. From temperature dependence oscillation amplitude we...
We have for the first time epitaxially grown superlattices of Y-Ba-Cu-O/Dy-Ba-Cu-O by dc magnetron sputtering onto ${\mathrm{SrTiO}}_{3}$ and MgO substrates. The wavelengths range from 24 (twice c axis) to 300 A\r{} x-ray diffractograms show satellite peaks characteristic multilayers each wavelength. 24-A\r{}-wavelength sample consists of, on average, alternate planes Y Dy. are superconducting with ${\mathrm{T}}_{\mathrm{c}0}$'s between 85 89 K, transition widths 2 resistivity ratios about 3.
We demonstrate that atomic force microscopy can be used to precisely manipulate individual sub-50 nm ferroelectric domains in ultrahigh density arrays on high-quality epitaxial Pb(Zr0.2Ti0.8)O3 thin films. Control of domain size was achieved by varying the strength and duration voltage pulses polarize material. Domain found depend logarithmically upon writing time linearly voltage. All domains, including those written with ∼100 ns pulses, remained completely stable for 7 day experiment.
We have studied the thermally activated flux-flow resistance in ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$/${\mathrm{PrBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ (YBCO/BrBCO) artificial superlattices magnetic fields perpendicular to a-b plane. find for multilayers with thick enough (>24 \AA{}) insulating PrBCO layers and YBCO thicknesses smaller than 300 \AA{} that activation energy has a logarithmic field dependence is proportional thickness multilayer.