Super-geometric electron focusing on the hexagonal Fermi surface of PdCoO₂.

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 PdCoO₂ gives rise to highly directional ballistic transport. We probe this directional ballistic regime in a single crystal of PdCoO₂ 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.

SUBMITTER: Bachmann MD 

PROVIDER: S-EPMC6841680 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature