Rocksalt rare-earth monoxides as electronic and magnetic materials

TL;DR

This paper reviews the synthesis, fundamental properties, and potential applications of rocksalt rare-earth monoxides, highlighting their unique electronic and magnetic behaviors that differ from traditional rare-earth oxides.

Contribution

It provides a comprehensive overview of the recent progress in synthesizing and understanding RE monoxides, emphasizing their promising electronic and magnetic properties for future materials research.

Findings

REOs are highly conductive and exhibit superconductivity.

REOs show room temperature ferromagnetism.

Recent synthesis via thin film epitaxy has enabled exploration of these materials.

Abstract

Stable binary rare earth (RE) oxides are usually trivalent RE ion sesquioxides (RE2O3), that are highly insulating and either nonmagnetic or antiferromagnetic. On the other hand, rocksalt-type divalent RE ion monoxides (REOs) have been scarcely synthesized owing to their metastable nature. Accordingly, their fundamental properties have not been unveiled. Recently, thin film epitaxy was successfully applied to synthesize various REOs. In stark contrast with RE2O3, REOs are highly electrically conducting, and exhibit superconductivity, room temperature ferromagnetism, and so on. Therefore, REOs are new and simple f-electron system, promising as electronic, magnetic, and spintronic materials. In this review, their fundamental properties are introduced, and their significance and future prospects are discussed toward a new paradigm in f-electron systems.