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