The nature of electron-electron and electron-lattice interactions in metallic oxides is revised. The common wisdom is that the strong correlations among electrons determine their properties. Here we argue that the unavoidable coupling between free electrons and the lattice in ionic materials leads to the formation of polarons. These are carriers dressed by a lattice distortion that travel with them and largely determine the transport and some optical properties.
Moreover, we argue that in early transition metal oxides, the Fermi surface has a cylindrical shape that limits the phonons available for scattering. Taking SrVO3 as illustrative example of a Fermi liquids, we demonstrate that both mechanisms can contribute to the ubiquitously observed quasi-T2 temperature dependence of the electrical resistivity in many metallic oxides. A new twist on the physics of Fermi liquids in ionic lattices.
Oxides for new-generation electronics
Electron–Phonon Coupling and Electron–Phonon Scattering in SrVO3
When illuminating a non-centrosymmetric material with light of energy higher than the bandgap, a net current appears because the electrons do not see the same electronic environment in one direction and the opposite direction, thus they hold a net momentum. This is the bulk photovoltaic effect (BPE), which depends on the light polarization.
Spin-charge conversion requires materials with a large spin-orbit coupling, which is typically obtained in heavy metal (Pt, etc.) ions. Here we demonstrate spin pumping across interfaces between metallic SrVO3, where V is a 3d1 ion, epitaxial thin films and ferromagnetic Ni80Fe20.
Building on recent developments in electronic-structure methods, we define and calculate the flexoelectric response of two-dimensional (2D) materials fully from first principles. In particular, we show that the open-circuit voltage response to a flexural deformation is a fundamental linear-response property of the crystal that can be calculated within the primitive unit cell of the flat configuration.
We present a complete structural study of the successive phase transitions observed in the YBaMn2O6 compound with the layered ordering of cations on the perovskite A-site. We have combined synchrotron radiation X-ray powder diffraction and symmetry-adapted mode analysis to describe the distorted structures as pseudosymmetric with respect to the parent tetragonal structure.
The development of new synthetic methodologies of perovskite oxynitrides is challenging but necessary for the search of new compounds and the investigation of new properties. Here, we report a new method of preparation of the perovskite LaTaON2 that has been investigated as a pigment and photocatalyst for water splitting.