Triple Point Topological Metals

TL;DR

This paper introduces a new class of topological quasiparticles called triple point fermions in metals with symmorphic crystal structures, revealing their unique properties and potential physical phenomena.

Contribution

The study reports the discovery of two distinct types of triple point fermions in metals, expanding the understanding of topological quasiparticles beyond those known in high-energy physics.

Findings

Identification of two types of triple point fermions

Examples of materials hosting these quasiparticles

Associated phenomena like Fermi arcs and Lifshitz transitions

Abstract

Topologically protected fermionic quasiparticles appear in metals, where band degeneracies occur at the Fermi level, dictated by the band structure topology. While in some metals these quasiparticles are direct analogues of elementary fermionic particles of the relativistic quantum field theory, other metals can have symmetries that give rise to quasiparticles, fundamentally different from those known in high-energy physics. Here we report on a new type of topological quasiparticles -- triple point fermions -- realized in metals with symmorphic crystal structure, which host crossings of three bands in the vicinity of the Fermi level protected by point group symmetries. We find two topologically different types of triple point fermions, both distinct from any other topological quasiparticles reported to date. We provide examples of existing materials that host triple point fermions of both types, and discuss a variety of physical phenomena associated with these quasiparticles, such as the occurrence of topological surface Fermi arcs, transport anomalies and topological Lifshitz transitions.