Ytterbium monoxide epitaxial thin films exhibit high electron mobility

Rare earth elements, such as ytterbium, scandium and lanthanides, are promising materials with applications in devices, both as insulators or semiconductors. While they have potential for use as electronic materials, they can be difficult to make. The new paper takes a first look at the optical and electrical properties of ytterbium monoxide (YbO) epitaxial thin films.

Previously, YbO polycrystalline powders were created in a high-pressure or carbon monoxide atmosphere, and YbO films were grown on a GaN base by molecular beam epitaxy. Yamamoto et al. report growing single crystalline YbO epitaxial thin films instead using pulsed laser deposition on YAlO₃ and CaF₂ substrates to study its optical and electrical properties.

An optical absorption spectrum was found showing three absorption peaks thought to be caused by electron shell transfers. The study’s results further noted high and tunable electrical conduction with high electron mobility at room temperature. The YbO was even found to be a narrow-gap semiconductor with variable electrical conduction by electron doping. These results are consistent chemical trends of ytterbium monochalcogenides (YbChs). At low temperatures, the results showed weak antilocalization behavior, which is thought to indicate significant spin-orbit coupling in the film, making YbO a promising material for heteroepitaxial spintronic devices.

Source: “High electron mobility with significant spin-orbit coupling in rock-salt YbO epitaxial thin film,” by Taku Yamamoto, Kenichi Kaminaga, Daichi Saito, Daichi Oka, and Tomoteru Fukumura, Applied Physics Letters (2019). The article can be accessed at https://doi.org/10.1063/1.5085938 .