Imaging the itinerant-to-localized transmutation of electrons across the metal-to-insulator transition

The most familiar physical property of materials is their ability to conduct (metals) or not (insulators) electric current. The conductivity of metals increases when the temperature decreases. Thus, copper conducts ten times better the current at 70K than at 600K. But for V2O3, a metal at room temperature, the conductivity drops sharply by a factor of a million when the temperature falls below 160K. It becomes a so-called Mott insulator! How to explain this astonishing transition? This work imaged for the first time how the itinerant, wave-like electrons in the metallic phase of V2O3 localize across the Mott metal-insulator transition. We will discuss the observed changes in electronic structure and compare them with other paradigmatic examples of metal-insulator transitions.

[1] M. Thees et al., Science Advances 7, eabj1164 (2021).