Giant anomalous Hall effect in a ferromagnetic Kagome-lattice semimetal

TL;DR

This paper reports a giant anomalous Hall effect in the ferromagnetic Kagome-lattice semimetal Co3Sn2S2, driven by its topological band structure and Berry curvature, with potential for quantum anomalous Hall state observation.

Contribution

It introduces Co3Sn2S2 as a magnetic Weyl semimetal with a Kagome lattice exhibiting a record-high anomalous Hall conductivity and angle, highlighting its topological properties and potential for quantum Hall states.

Findings

Anomalous Hall conductivity of 1130 S/cm observed.

Anomalous Hall angle reaches 20%, an order of magnitude larger than typical systems.

Negative magnetoresistance consistent with Weyl fermions and chiral anomaly.

Abstract

Magnetic Weyl semimetals with broken time-reversal symmetry are expected to generate strong intrinsic anomalous Hall effects, due to their large Berry curvature. Here, we report a magnetic Weyl semimetal candidate Co3Sn2S2 with a quasi-two-dimensional crystal structure consisting of stacked Kagome lattices. This lattice provides an excellent platform for hosting exotic quantum topological states. We observe a negative magnetoresistance that is consistent with the chiral anomaly expected from the presence of Weyl fermions close to the Fermi level. The anomalous Hall conductivity is robust against both increased temperature and charge conductivity, which corroborates the intrinsic Berry-curvature mechanism in momentum space. Owing to the low carrier density in this material and the significantly enhanced Berry curvature from its band structure, the anomalous Hall conductivity and the anomalous Hall angle simultaneously reach 1130 S cm-1 and 20%, respectively, an order of magnitude larger than typical magnetic systems. Combining the Kagome-lattice structure and the long-range out-of-plane ferromagnetic order of Co3Sn2S2, we expect that this material is an excellent candidate for observation of the quantum anomalous Hall state in the two-dimensional limit.