# Evolution of a band insulating phase from a correlated metallic phase

## TL;DR

This study explores how the electronic structure of SrRu_(1-x)Ti_xO_3 evolves from metallic to insulating phases, revealing a complex interplay of disorder and electron correlation through spectroscopy and theoretical analysis.

## Contribution

It provides detailed experimental and theoretical insights into the metal-insulator transition and the role of disorder and correlation in SrRu_(1-x)Ti_xO_3.

## Key findings

- Surface spectra show a metal-insulator transition at x=0.5 with a soft gap.
- Bulk spectra reveal a pseudogap and broadening of spectral features with increasing x.
- First-principles calculations capture high-energy anomalous evolutions.

## Abstract

We investigate the evolution of the electronic structure in SrRu_(1-x)Ti_xO_3 as a function of x using high resolution photoemission spectroscopy, where SrRuO3 is a weakly correlated metal and SrTiO3 is a band insulator. The surface spectra exhibit a metal-insulator transition at x = 0.5 by opening up a soft gap. A hard gap appears at higher x values consistent with the transport properties. In contrast, the bulk spectra reveal a pseudogap at the Fermi level, and unusual evolution exhibiting an apparent broadening of the coherent feature and subsequent decrease in intensity of the lower Hubbard band with the increase in x. Interestingly, the first principle approaches are found to be sufficient to capture anomalous evolutions at high energy scale. Analysis of the spectral lineshape indicates strong interplay between disorder and electron correlation in the electronic properties of this system.