Interfacial B-site atomic configuration in polar (111) and non-polar (001) SrIrO3/SrTiO3 heterostructures

T J Anderson,J J Patzner,L Xie,C B Eom,S Ryu,H Zhou,J P Podkaminer,X Q Pan

doi:10.1063/1.4993170

Abstract

The precise control of interfacial atomic arrangement in ABO3 perovskite heterostructures is paramount, particularly in cases where the subsequent electronic properties of the material exhibit geometrical preferences along polar crystallographic directions that feature inevitably complex surface reconstructions. Here, we present the B-site interfacial structure in polar (111) and non-polar (001) SrIrO3/SrTiO3 interfaces. The heterostructures were examined using scanning transmission electron microscopy and synchrotron-based coherent Bragg rod analysis. Our results reveal the preference of B-site intermixing across the (111) interface due to the polarity-compensated SrTiO3 substrate surface prior to growth. By comparison, the intermixing at the non-polar (001) interface is negligible. This finding suggests that the intermixing may be necessary to mitigate epitaxy along heavily reconstructed and non-stoichiometric (111) perovskite surfaces. Furthermore, this preferential B-site configuration could allow the geometric design of the interfacial perovskite structure and chemistry to selectively engineer the correlated electronic states of the B-site d-orbital.

Highlights

Progress in the design and synthesis of artificial perovskite oxide thin film heterostructures has led to the realization of emergent and exotic material properties, at the heterostructure interfaces.[1,2,3] While the majority of these studies involve thin film growth along the (001) direction, there has recently been significant theory work predicting topological insulators,[4,5] flat bands with a non-zero Chern number,[6] and various correlated electronic phases[7,8,9] in perovskite oxide heterostructures synthesized along the (111) direction
Our choice of SrIrO3 and SrTiO3 eliminated the possibility of A-site cation intermixing, which isolated our study to the B-site behavior
The SrIrO3/SrTiO3 heterostructures were grown with atomic layer precision using pulsed laser deposition with in situ reflection high energy electron diffraction (RHEED)

Summary

Introduction

Progress in the design and synthesis of artificial perovskite oxide thin film heterostructures has led to the realization of emergent and exotic material properties, at the heterostructure interfaces.[1,2,3] While the majority of these studies involve thin film growth along the (001) direction, there has recently been significant theory work predicting topological insulators,[4,5] flat bands with a non-zero Chern number,[6] and various correlated electronic phases[7,8,9] in perovskite oxide heterostructures synthesized along the (111) direction. 2. [(a) and (b)] RHEED intensity of the specular diffraction spot for the (111) and (001) SrTiO3/SrIrO3 heterostructures, respectively, showing layer-by-layer growth except in the case of the (111) SrTiO3 capping film.

Results

Conclusion