Low-loss tunable infrared plasmons in the high-mobility perovskite (Ba,La)SnO$_3$

TL;DR

This study demonstrates that La-doped BaSnO$_3$ supports long-lived, highly confined infrared plasmons with low loss, highlighting its potential for nanoscale optoelectronic applications as a high-mobility, tunable plasmonic material.

Contribution

The paper provides the first systematic investigation of infrared localized surface plasmons in high-mobility La-doped BaSnO$_3$, revealing their confinement, low damping, and relation to carrier mobility.

Findings

BLSO supports long-lived infrared plasmons.

Localized surface plasmons in BLSO are highly confined.

Plasmon damping correlates with carrier mobility.

Abstract

BaSnO$_3$ exhibits the highest carrier mobility among perovskite oxides, making it ideal for oxide electronics. Collective charge carrier oscillations, plasmons, are expected to arise in this material, thus providing a tool to control the nanoscale optical field for optoelectronics applications. Here, we demonstrate the existence of relatively long-lived plasmons supported by high-mobility charge carriers in La-doped BaSnO$_3$ (BLSO). By exploiting the high spatial and energy resolution of electron energy-loss spectroscopy with a focused beam in a scanning transmission electron microscope, we systematically investigate the dispersion, confinement ratio, and damping of infrared localized surface plasmons (LSP) in BLSO nanoparticles. We find that the LSPs in BLSO are highly spatially confined compared to those sustained by noble metals and have relatively low loss and high quality factor compared to other doped oxides. Further analysis clarifies the relation between plasmon damping and carrier mobility in BLSO. Our results support the use of nanostructured degenerate semiconductors for plasmonic applications in the infrared region and establish a relevant alternative to more traditional plasmonic materials.