Isostructural Metal-Insulator Transition Driven by Dimensional-Crossover in SrIrO3 Heterostructures

TL;DR

This study demonstrates an isostructural metal-insulator transition in SrIrO3 films driven by dimensional crossover, where the bandwidth reduction of Jeff=3/2 states causes the transition without structural change.

Contribution

It provides experimental evidence of a bandwidth-controlled MIT in isostructural SrIrO3 films, isolating the effect of dimensionality from structural phase transitions.

Findings

Dimensional crossover induces MIT in SrIrO3 without structural change.

Bandwidth of Jeff=3/2 states decreases with reduced dimensionality.

The transition is driven by bandwidth reduction, not structural or magnetic phase changes.

Abstract

Dimensionality reduction induced metal-insulator transitions in oxide heterostructures are usually coupled with structural and magnetic phase transitions, which complicate the interpretation of the underlying physics. Therefore, achieving isostructural MIT is of great importance for fundamental physics and even more for applications. Here, we report an isostructural metal-insulator transition driven by dimensional-crossover in spin-orbital coupled SrIrO3 films. By using in-situ pulsed laser deposition and angle-resolved photoemission spectroscopy, we synthesized and investigated the electronic structure of SrIrO3 ultrathin films with atomic-layer precision. Through inserting orthorhombic CaTiO3 buffer layers, we demonstrate that the crystal structure of SrIrO3 films remains bulk-like with similar oxygen octahedra rotation and tilting when approaching the ultrathin limit. We observe that a dimensional-crossover metal-insulator transition occurs in isostructural SrIrO3 films. Intriguingly, we find the bandwidth of Jeff=3/2 states reduces with lowering the dimensionality and drives the metal-insulator transition. Our results establish a bandwidth controlled metal-insulator transition in the isostructural SrIrO3 thin films.