Fabrication of (111)-oriented Ca0.5Sr0.5IrO3/SrTiO3 superlattices; a designed playground for honeycomb physics

TL;DR

This paper reports the successful fabrication of (111)-oriented Ca0.5Sr0.5IrO3/SrTiO3 superlattices, revealing magnetic insulating ground states and providing a platform to explore honeycomb physics and topological states.

Contribution

It introduces a method to create atomically precise (111)-oriented superlattices with potential topological and magnetic properties, advancing materials design for quantum physics.

Findings

Superlattice structures confirmed by x-ray diffraction and TEM.

Ground states are magnetic insulators, indicating strong electron correlations.

Potential for topological states in bilayer films with honeycomb Ir sub-lattice.

Abstract

We report the fabrication of (111)-oriented superlattice structures with alternating 2m-layers (m = 1, 2, and 3) of Ca0.5Sr0.5IrO3 perovskite and two layers of SrTiO3 perovskite on SrTiO3(111) substrates. In the case of m = 1 bilayer films, the Ir sub-lattice is a buckled honeycomb, where a topological state may be anticipated. The successful growth of superlattice structures on an atomic level along the [111] direction was clearly demonstrated by superlattice reflections in x-ray diffraction patterns and by atomically-resolved transmission electron microscope images. The ground states of the superlattice films were found to be magnetic insulators, which may suggest the importance of electron correlations in Ir perovskites in addition to the much discussed topological effects.