Electrons in insulating crystals polarize in response to an externally applied electric field, resulting in a partial suppression of the field amplitude; such a phenomenon is known as “dielectric screening.” While much effort has gone into developing a quantitative understanding of this behavior and its impact on materials properties, 2D crystals remain challenging to describe by means of established modeling strategies.
The proximity of a thermodynamic triple point and the formation of transient metastable phases may result in complex phase and microstructural trajectories across the metal-insulator transition in strained VO2 films. A detailed analysis using in-situ synchrotron X-ray diffraction unveils subtle fingerprints of this complexity in the structure of epitaxial films. During phase transition the low-temperature monoclinic M1 phase is constrained along the R planes by the coexisting high-temperature R phase domains, which remain epitaxially clamped to the substrate.
Endurance of ferroelectric HfO2 needs to be enhanced for its use in commercial memories. This work investigates fatigue in epitaxial Hf0.5Zr0.5O2 (HZO) instead of polycrystalline samples. Using different substrates, the relative amount of orthorhombic (ferroelectric) and monoclinic (paraelectric) phases is controlled. Epitaxial HZO films almost free of parasitic monoclinic phase suffer severe fatigue. In contrast, fatigue is mitigated in films with a greater amount of paraelectric phase.
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 YBaMn2O6 compound shows three consecutive phase transitions on cooling from 603 K down to 100 K. It undergoes a first-order structural transition at T1 ≈ 512 K from a C2/m cell with a single Mn site to a P21/c cell with two nonequivalent Mn sites.
Oxygen packaging in transition metal oxides determines the metal-oxygen hybridization and electronic occupation at metal orbitals. Strontium vanadate (SrVO3), having a single electron in a 3d orbital, is thought to be the simplest example of strongly correlated metallic oxides. Here, we determine the effects of epitaxial strain on the electronic properties of SrVO3 thin films, where the metal-oxide sublattice is corner connected.