Though first order transitions are thought to be abrupt, materials find cunning ways to smooth the jump. Here we show that VO2 chooses making beautiful tapestries at the atomic scale. To see how, and how they affect its intriguing metal-insulator transition, continue reading:
The observation of electronic phase separation textures in vanadium dioxide, a prototypical electron‐correlated oxide, has recently added new perspectives on the long standing debate about its metal–insulator transition and its applications. Yet, the lack of atomically resolved information on phases accompanying such complex patterns still hinders a comprehensive understanding of the transition and its implementation in practical devices. In this work, atomic resolution imaging and spectroscopy unveils the existence of ferroelastic tweed structures on ≈ 5 nm length scales, well below the resolution limit of currently used spectroscopic imaging techniques. Moreover, density functional theory calculations show that this pretransitional fine‐scale tweed, which on average looks and behaves like the standard metallic rutile phase, is in fact weaved by semi‐dimerized chains of vanadium in a new monoclinic phase that represents a structural bridge to the monoclinic insulating ground state. These observations provide a multiscale perspective for the interpretation of existing data, whereby phase coexistence and structural intermixing can occur all the way down to the atomic scale.
Oxides for new-generation electronics
Metallic Diluted Dimerization in VO2 Tweeds
Felip Sandiumenge, Laura Rodríguez, Miguel Pruneda, César Magén, José Santiso, Gustau Catalan
The layered perovskite YBaCuFeO5 (YBCFO) is considered one of the best candidates to high-temperature chiral multiferroics with strong magnetoelectric coupling. In RBaCuFeO5 perovskites (R: rare-earth or Y) A-site cations are fully ordered whereas their magnetic properties strongly depend on the preparation process. They exhibit partial cationic disorder at the B-site that generates a magnetic spiral stabilized through directionally assisted long range coupling between canted locally frustrated spins.
We report the synthesis and theoretical study of two new colorimetric chemosensors with special selectivity and sensitivity to Ni2+ and Cu2+ ions over other metal cations in the CH3CN/H2O solution. Compounds (E)-4-((2-nitrophenyl)diazenyl)-N,N-bis(pyridin-2-ylmethyl)aniline (A) and (E)-4-((3-nitrophenyl)diazenyl)-N,N-bis(pyridin-2-ylmethyl)aniline (B) exhibited a drastic color change from yellow to colorless, which allows the detection of the mentioned metal cations through different techniques.
Early detection of diabetes, a worldwide health issue, is key for its successful treatment. Acetone is a marker of diabetes, and efficient, non-invasive detection can be achieved with the use of nanotechnology. In this paper we investigate the effect of acetone adsorption on the electronic properties of silicon nanowires (SiNWs) by means of density functional theory.
The development of advanced piezoelectric α‐quartz microelectromechanical system (MEMS) for sensing and precise frequency control applications requires the nanostructuration and on‐chip integration of this material on silicon material.
Epitaxial orthorhombic Hf0.5Zr0.5O2 (HZO) films on La0.67Sr0.33MnO3 (LSMO) electrodes show robust ferroelectricity, with high polarization, endurance and retention. However, no similar results have been achieved using other perovskite electrodes so far. Here, LSMO and other perovskite electrodes are compared.