Super-geometric electron focusing on the hexagonal Fermi surface of PdCoO<sub>2</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31705049.
- Also identified by DOI 10.1038/s41467-019-13020-9 and PMC identifier 6841680.
- 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
Geometric electron optics may be implemented in solids when electron transport is ballistic on the length scale of a device. Currently, this is realized mainly in 2D materials characterized by circular Fermi surfaces. Here we demonstrate that the nearly perfectly hexagonal Fermi surface of PdCoO<sub>2</sub> gives rise to highly directional ballistic transport. We probe this directional ballistic regime in a single crystal of PdCoO<sub>2</sub> by use of focused ion beam (FIB) micro-machining, defining crystalline ballistic circuits with features as small as 250 nm. The peculiar hexagonal Fermi surface naturally leads to enhanced electron self-focusing effects in a magnetic field compared to circular Fermi surfaces. This super-geometric focusing can be quantitatively predicted for arbitrary device geometry, based on the hexagonal cyclotron orbits appearing in this material. These results suggest a novel class of ballistic electronic devices exploiting the unique transport characteristics of strongly faceted Fermi surfaces.