Zero‐Strain Metal‐Insulator Transition by the Local Fluctuation of Cation Dimerization

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Abstract
The coupled electronic and structural transitions in metal‐insulator transition (MIT) hinder ultrafast switching and ultimate endurance. Decoupling these transitions and achieving a zero‐strain electronic MIT can overcome the fundamental limitations of MIT in solid materials. Here, this study demonstrates that iso‐valent Ti dopants in supercooled VO2 epitaxial films cause MIT with minimal hysteresis without changing unit‐cell volume and crystal symmetry. The Ti dopants in the VO2 lattice locally alter the configuration of V‐V pairs, where the long‐range ordering in V‐V pairs is disrupted, and the nano‐domains of V‐V dimers are formed. Strikingly, these local V‐V dimers persist even above the electronic transition temperature (TMI), facilitating the zero‐strain electronic MIT with nanoscale structural heterogeneity. The geometrically compatible interface between insulating and metallic phases drastically enhances switching speed and endurance during electrically and optically driven zero‐strain MIT. This discovery offers a fresh perspective on the scientific understanding of MIT and the improved functionality in terms of device speed and reliability by decoupling electronic and structural transitions.
Funding Information
  • National Research Foundation of Korea (2020R1A2C2006389, 2022M3F3A2A03015405)
  • Ministry of Science and ICT, South Korea (RS‐2024‐00445552, RS‐2024‐00437208, RS‐2024‐00355591, RS‐2023‐00258227)
  • Ministry of Trade, Industry and Energy (RS‐2024‐00405798)
  • Korea Basic Science Institute (2021R1A6C101A429, 2020R1A6C101A202)
  • U.S. Department of Energy

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