Imaging the itinerant-to-localized transmutation of electrons across the metal-to-insulator transition in V$_2$O$_3$

TL;DR

This study uses ARPES to directly observe how electrons in V$_2$O$_3$ transition from itinerant to localized states across the metal-insulator transition, revealing the disappearance of conduction bands and shifts in localized states.

Contribution

It provides the first direct energy- and momentum-resolved evidence of the electron transition mechanism in V$_2$O$_3$ during the MIT.

Findings

Disappearance of itinerant conduction band during MIT

Shift of localized state to larger binding energies

No change in energy-momentum dispersion of the conduction band

Abstract

In solids, strong repulsion between electrons can inhibit their movement and result in a "Mott" metal-to-insulator transition (MIT), a fundamental phenomenon whose understanding has remained a challenge for over 50 years. A key issue is how the wave-like itinerant electrons change into a localized-like state due to increased interactions. However, observing the MIT in terms of the energy- and momentum-resolved electronic structure of the system, the only direct way to probe both itinerant and localized states, has been elusive. Here we show, using angle-resolved photoemission spectroscopy (ARPES), that in V$_2$O$_3$ the temperature-induced MIT is characterized by the progressive disappearance of its itinerant conduction band, without any change in its energy-momentum dispersion, and the simultaneous shift to larger binding energies of a quasi-localized state initially located near the Fermi level.