Directional picoantenna behavior of tunnel junctions formed by an atomic-scale surface defect.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39321296.
- Also identified by DOI 10.1126/sciadv.adn2295 and PMC identifier 11423879.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Plasmonic nanoantennas have attracted much attention lately, among other reasons because of the directionality of light emitted by fluorophores coupled to their localized surface plasmon resonances. Plasmonic picocavities, i.e., cavities with mode volumes below 1 nm<sup>3</sup>, could act as enhanced antennas due to their extreme field confinement, but the directionality on their emission is difficult to control. In this work, we show that the plasmonic picocavity formed between the tip of a scanning tunneling microscope and a metal surface with a monoatomic step shows directional emission profiles and, thus, can be considered as a realization of a picoantenna. Electromagnetic calculations demonstrate that the observed directionality arises from the reshaping and tilting of the surface charges induced at the scanning tip due to the atomic step. Our results pave the way to exploiting picoantennas as an efficient way for the far-field probing and control of light-matter interactions below the nanoscale.