Theoretical study of topological properties of ferromagnetic pyrite CoS₂

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 CoS2, 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 CoS2 is a promising platform to study topological phenomena, as well as a good candidate for spintronic applications.

Influence of topology on the phase transition of a ferromagnetic metal

“…1 E , where entanglement of spin-up and spin-down states is due to the spin–orbit interaction. The band inversion, which was reported in earlier LSDA calculations ( 7 , 10 ) and angle-resolved photoemission spectrscopy measurements ( 7 ), resembles that of the non spin-polarized bands in a topological insulator ( 22 ).…”

“…Band inversion, where the minority-spin electron pocket crosses a majority-spin e g band about 0.040 eV above E F results in a 0.015 eV gap at the crossing point. Recent work confirmed this feature ( 10 ), and revealed an exceptionally low residual resistivity and high positive magnetoresistance ( 11 ) that are associated with Weyl points at E F .…”

Scaling of Berry-curvature monopole dominated large linear positive magnetoresistance

“…Recently, the pyrite CoS 2 was reported as a magnetic Weyl semimetal candidate ( 43 , 44 ). In this study, we found that CoS 2 bears many Weyl nodes and a large LPMR.…”