Interface doping and the effect of strain and oxygen stoichiometry on the transport and electronic structure properties of SrIrO$_3$ heterostructures

TL;DR

This study investigates how interface doping, strain, and oxygen stoichiometry influence the electronic and transport properties of SrIrO$_3$ heterostructures, revealing pathways to tune their quantum phases and topological states.

Contribution

It demonstrates that growth conditions and strain can be used to control the electronic structure and carrier concentration in SrIrO$_3$ thin films, enabling tuning of quantum and topological properties.

Findings

Distinct electronic structures were observed under different growth parameters.

Density functional theory matched X-ray spectra, identifying key electronic states.

Controlling growth regimes can enhance specific carrier types at the Fermi level.

Abstract

The 5$d$ series semimetallic Dirac nodal-line perovskite SrIrO$_3$ presents a promising system to study the interplay between spin-orbit coupling and electron-electron interactions in the epitaxial thin film geometry. The competition between the band splitting and the suppression of the correlation energy, from the extended d orbitals can influence the electronic and magnetic structure and lead to exotic quantum phases in such systems. This iridate member possesses a phase diagram which is acutely sensitive to both heterostructure growth conditions and geometric strain, which stabilises the orthorhombic phase over the monoclinic bulk crystal structure. The growth mode and lattice constants of this iridate perovskite have been observed to vary sharply with oxygen partial pressure and thickness during growth by pulsed laser deposition. In this study the structural and transport properties originating from two sets of growth parameters have been compared, indicating distinct differences in the electronic structure at the Fermi edge. Density functional theory calculations of the convolved density of states compared with the X-ray photoemission spectra near the Fermi edge allow the identification of the states contributing to the electronic structure in this region. The spectral differences between these case studies indicate that controlling the growth regime could enable the tuning of the electronic structure to promote enhanced concentrations of one carrier type over another at the Fermi level in this nominally semimetallic system. The control of the correlation-induced electronic transport parameters in this system will enable access to the spin-orbital entangled states and the topological crystalline properties associated with the honeycomb lattice in this Mott system.