Correlated Quantum Phenomena of Spin–Orbit Coupled Perovskite Oxide Heterostructures: Cases of SrRuO₃ and SrIrO₃ Based Artificial Superlattices

Abstract

Unexpected, yet useful functionalities emerge when two or more materials merge coherently. Artificial oxide superlattices realize atomic and crystal structures that are not available in nature, thus providing controllable correlated quantum phenomena. This review focuses on 4d and 5d perovskite oxide superlattices, in which the spin–orbit coupling plays a significant role compared with conventional 3d oxide superlattices. Modulations in crystal structures with octahedral distortion, phonon engineering, electronic structures, spin orderings, and dimensionality control are discussed for 4d oxide superlattices. Atomic and magnetic structures, Jeff = 1/2 pseudospin and charge fluctuations, and the integration of topology and correlation are discussed for 5d oxide superlattices. This review provides insights into how correlated quantum phenomena arise from the deliberate design of superlattice structures that give birth to novel functionalities.

Advances in complex oxide quantum materials through new approaches to molecular beam epitaxy

“…Heterostructures based on iridates and other transition metal oxides are being actively investigated that allows for fine tuning of interfacial effects. Particularly, SrIrO 3 is interfaced with magnetic complex oxides such as LaMnO 3 and SrRuO 3 that may result in interfacial topological textures [189][190][191][192]. At the interface of this high spin-orbit coupled material, charge transfer, combined with symmetry breaking and hybridization effects, may allow the development of novel phases.…”

Interfacial Electronic and Magnetic Reconstructions in Manganite/Titanate Superlattices

“…Complex oxides have demonstrated a wide spectrum of novel functionalities, including high-temperature superconductor, [1] DOI: 10.1002/admi.202300903 spin polarization, [2] colossal magnetoresistance, [3] and ferroelectric (FE) properties. [4] Epitaxial heterostructures of complex oxides [5] offered opportunities to achieve exotic properties from the strong entanglements among various interfacial effects, such as the structural proximity effect, [6] charge transfer, [7] orbital reconstruction, [8] interlayer exchange coupling, [9] polarity catastrophe, [10] spin-orbit coupling, [11] etc. 2D electron gas between two band insulators; [10] interfacial magnetism between two nonmagnetic oxides; [12] and antiferromagnetic (AFM) coupling between two ferromagnets [9,13] are just a few examples of the active fields of research on dominant interfacial effects of perovskite heterostructures.…”

Exotic Magnetic Anisotropy Near Digitized Dimensional Mott Boundary

“…The vast material possibilities and delicate thickness control in superlattices offer facile control knobs of correlated functionalities, including dimensionality-induced MIT, magnetic phase transition, exchange bias, and magnetic anisotropy engineering. [16][17][18][19][20] One way of measuring the anisotropy in low-dimensional synthetic crystals would be to assess the ratio between the intralayer and interlayer interactions. For a superlattice composed of monolayers of ferromagnetic metal and sufficiently thick layers of nonmagnetic insulator, interlayer coupling between the magnetic monolayers is expected to disappear, leading to 2D confinement (Figure 1a).…”