Direct visualization of percolating metal-insulator transition in V2O3 using scanning microwave impedance microscopy

TL;DR

This study uses scanning microwave impedance microscopy to directly visualize the percolation process during the metal-insulator transition in V2O3, revealing hysteresis and domain dynamics linked to structural-electronic decoupling.

Contribution

It provides the first direct microscopic imaging of percolation and hysteresis in V2O3's MIT, connecting structural and electronic transitions.

Findings

Percolation threshold identified via microwave impedance imaging

Hysteretic conductance behavior observed during transition

Different domain nucleation processes upon cooling and warming

Abstract

Using the extensively studied V2O3 as a prototype system, we investigate the role of percolation in metal-insulator transition (MIT). We apply scanning microwave impedance microscopy to directly determine the metallic phase fraction p and relate it to the macroscopic conductance G, which shows a sudden jump when p reaches the percolation threshold. Interestingly, the conductance G exhibits a hysteretic behavior against p, suggesting two different percolating processes upon cooling and warming. Based on our image analysis and model simulation, we ascribe such hysteretic behavior to different domain nucleation and growth processes between cooling and warming, which is likely caused by the decoupled structural and electronic transitions in V2O3 during MIT. Our work provides a microscopic view of how the interplay of structural and electronic degrees of freedom affects MIT in strongly correlated systems.