Observation of new intrinsic properties of VO2

TL;DR

This study reveals new intrinsic properties of VO2, including distinct structural phase transitions and transition behaviors at specific temperatures, highlighting complex mechanisms behind its metal-insulator transition.

Contribution

It provides detailed synchrotron x-ray microdiffraction analysis of VO2's phase transitions, uncovering the nature of its insulator-insulator and metal-insulator transitions.

Findings

IIT shows percolative structural phase transition

MIT exhibits an abrupt, non-percolative transition

MIT occurs with a sharp boundary and variable onset temperature

Abstract

The single crystal VO2, exihibiting a first-order metal-insulator transition (MIT) at 67.2 degrees C and an insulator-insulator transition (IIT) at ~49.7 degrees C, is grown. From synchrotron-based x-ray microdiffraction analysis, the IIT shows structural phase transition (SPT) of monoclinic M2 to M1 phases while the MIT displays M1 to rutile R phases. The IIT exhibits percolative SPT while the MIT shows abrupt transition width of < 0.02 degrees C, supporting Mott's prediction. The MIT occurs non-percolatively with a sharp boundary between R and M1 phases. The MIT onset temperature shows significant variation.