Theoretical study of topological properties of ferromagnetic pyrite CoS$_2$

TL;DR

This study reveals that the well-known ferromagnetic pyrite CoS$_2$ exhibits rich topological features such as Weyl nodes, nodal lines, and surface states, making it a promising material for topological physics and spintronics.

Contribution

The paper provides the first detailed analysis of topological properties in CoS$_2$, identifying Weyl nodes, nodal lines, and surface states in a well-studied ferromagnetic material.

Findings

Identification of Weyl nodes and nodal lines in CoS$_2$

Observation of spin-polarized Fermi arcs and drumhead states

CoS$_2$ as a candidate for topological and spintronic applications

Abstract

Since the discovery of the first topological material 15 years ago, the search for material realizations of novel topological phases has become the driving force of the field. While oftentimes we search for new materials, we forget that well established materials can also display very interesting topological properties. In this work, we revisit CoS$_2$ , a metallic ferromagnetic pyrite that has been extensively studied in the literature due to its magnetic properties. We study the topological features of its electronic band structure and identify Weyl nodes and Nodal lines, as well as a symmetry-protected 4-fold fermion close to the Fermi level. Looking at different surface cleavage planes, we observe both spin polarized Fermi arcs in the majority channel and drumhead states. These findings suggest that CoS$_2$ is a promising platform to study topological phenomena, as well as a good candidate for spintronic applications.