Research progress of metal-insulator phase transition in VO<sub>2</sub> induced by electric field

Abstract

Vanadium dioxide (VO<sub>2</sub>) is a typical representative of strongly correlated electronic systems, which undergoes a reversible transition from the insulator phase to metal phase, induced by a certain threshold for each of temperature, electric field, illumination and pressure. The crystal structure of VO<sub>2</sub> will undergo a reversible transition from monoclinic structure to tetragonal rutile structure when the phase transition happens, which is considered as the microscopic mechanism of VO<sub>2</sub> metal-insulator transition (MIT). The conductivity of VO<sub>2</sub> can be increased by 2—5 orders of magnitude when the MIT is induced by electric field, which makes VO<sub>2</sub> possess good application prospects in the fields of restructurable slot antenna, terahertz radiation, intelligent electromagnetic protection materials, etc. Therefore, the reversible metal-insulator phase transition in VO<sub>2</sub>, induced by electric field, has long been a research hotspot, which however, has been seldom reported. Firstly, in this paper, the changes of the crystal structure and energy band structure of VO<sub>2</sub> during MIT are introduced briefly. The methods of regulating the phase transition are given, including temperature control, bandwidth and band-filling control. Then, the important discovery and research progress of VO<sub>2</sub> MIT induced by electric field based on the research method, response time, critical threshold field and phase transition mechanism are summarized and reviewed comprehensively. The method of studying the VO<sub>2</sub> phase transition relates to its structure, including planar structure, three-terminal gated ?eld effect switch and sandwiched layer structure. The sandwich layer structure is more suitable for investigating the MIT characteristics of VO<sub>2</sub> in experimental stage because of its structural advantage of preparation and test. The response time of VO<sub>2</sub> MIT can be completed in nanoseconds, of which the substantial parameter has been revealed by many reports, also including the excellent reversibility of VO<sub>2</sub> MIT. The MIT critical threshold field of the VO<sub>2</sub> film can be tuned by element doping, coexistence of multivalent vanadium oxides and multiple physical field synergism effectively. The MIT mechanism of VO<sub>2</sub> induced by electric field has been proposed so far, which includes joule heating mechanism and pure electric field mechanism, and the latter is considered to be more likely to give a reasonable explanation. Finally, in the paper the current problems of the VO<sub>2</sub> MIT research and the near-future development direction of the VO<sub>2</sub> MIT materials are also pointed out.