The electronic structure of epitaxially stabilized 5d perovskite Ca_{1-x}Sr_xIrO_3 (x = 0, 0.5, and 1) thin films: the role of strong spin-orbit coupling

TL;DR

This study explores the electronic structure of epitaxially stabilized Ca_{1-x}Sr_xIrO_3 thin films, revealing how strong spin-orbit coupling influences their metal-insulator transition and electronic properties across different compositions.

Contribution

It demonstrates the stabilization of perovskite Ca_{1-x}Sr_xIrO_3 phases via epitaxial growth and analyzes how spin-orbit coupling affects their electronic states and phase boundary proximity.

Findings

Transport properties vary systematically with x from insulating to metallic.

Strong spin-orbit coupling leads to Jeff=1/2 and 3/2 states.

Electrical properties are sensitive to composition and strain.

Abstract

We have investigated the electronic structure of meta-stable perovskite Ca1-xSrxIrO3 (x = 0, 0.5, and 1) thin films using transport measurements, optical spectroscopy, and first-principles calculations. We artificially fabricated the perovskite phase of Ca1-xSrxIrO3, which has a hexagonal or post perovskite crystal structure in bulk form, by growing epitaxial thin films on perovskite GdScO3 substrates using epi-stabilization technique. The transport properties of the perovskite Ca1-xSrxIrO3 films systematically changed from nearly insulating (or semi-metallic) for x = 0 to bad metallic for x = 1. Due to the extended wavefunctions, 5d electrons are usually delocalized. However, the strong spin-orbit coupling in Ca1-xSrxIrO3 results in the formation of effective total angular momentum Jeff = 1/2 and 3/2 states, which puts Ca1-xSrxIrO3 in the vicinity of a metal-insulator phase boundary. As a result, the electrical properties of the Ca1-xSrxIrO3 films are found to be sensitive to x and strain.