Anomalous Hall conductivity and Berry phase in CoS₂

In Weyl semimetals (WSMs), the conduction and valence bands intersect at distinct points on the Brillouin zone known as Weyl points, which act as monopoles of Berry curvature in momentum space. This nontrivial band topology, confirmed from ab initio calculations, gives rise to various exotic transport properties, such as a giant anomalous Hall effect (AHE), negative magnetoresistance, the planar Hall effect, and the anomalous Nernst effect. These features in magnetotransport are key indicators of the Weyl nature of the electronic bands. Combined ab initio calculations and measurements of transport and magnetic properties of CoS₂ confirm its half-metallic characteristics as also evidenced from the temperature-dependent resistivity data. A Negative to positive magneto-resistance transition is observed above the ordering temperature. Experimental observation of anomalous Hall resistivity and ab initio computed band structure and Berry curvature demonstrate that the AHE is primarily driven by the intrinsic Karplus–Luttinger contribution, often linked to Berry phase physics and the side-jump mechanism.