Sixfold fermion near the Fermi level in cubic PtBi2

TL;DR

This paper identifies cubic PtBi2 as a topological semimetal with a sixfold band crossing near the Fermi level, and explores how magnetic fields influence its exotic fermionic excitations, making it a promising platform for studying novel topological transport phenomena.

Contribution

The study combines experimental ARPES measurements with theoretical modeling to reveal a sixfold fermion in PtBi2 and analyzes its magnetic field response, advancing understanding of complex topological semimetals.

Findings

PtBi2 hosts a sixfold band touching point near the Fermi level.

Magnetic field splits the sixfold fermion into twenty Weyl cones.

Experimental results agree with density functional theory calculations.

Abstract

We show that the cubic compound PtBi2, is a topological semimetal hosting a sixfold band touching point in close proximity to the Fermi level. Using angle-resolved photoemission spectroscopy, we map the bandstructure of the system, which is in good agreement with results from density functional theory. Further, by employing a low energy effective Hamiltonian valid close to the crossing point, we study the effect of a magnetic field on the sixfold fermion. The latter splits into a total of twenty Weyl cones for a Zeeman field oriented in the diagonal, [111] direction. Our results mark cubic PtBi2, as an ideal candidate to study the transport properties of gapless topological systems beyond Dirac and Weyl semimetals.