Quantum oscillations reveal sixfold fermions in cubic $\beta$-PtBi$_2$

TL;DR

This study combines experimental quantum oscillation measurements with theoretical calculations to identify sixfold fermions near the Fermi level in cubic $eta$-PtBi$_2$, revealing new topological fermionic states.

Contribution

It provides the first experimental evidence of sixfold fermions in cubic $eta$-PtBi$_2$ through combined oscillation and density functional theory analysis.

Findings

Identification of three small electron pockets near the Fermi level.

Confirmation of sixfold band-touching points at the R point.

Establishment of sixfold fermions as relevant low-energy excitations.

Abstract

We report a study of de Haas-van Alphen oscillations in high-quality single crystals of cubic $\beta$-PtBi$_2$. In combination with density functional theory calculations, we identify quantum oscillations associated with all Fermi surface sheets predicted by theory. Our results uncover three small electron pockets centered on a sixfold band-touching point located approximately 25 meV below the Fermi level at the $R$ point of the Brillouin zone. These findings firmly establish the presence of sixfold fermions in close proximity to the Fermi energy of $\beta$-PtBi$_2$.