Magnetic field

Magnetoresistance

Physics

Hall effect

Position and momentum space

Chiral anomaly

Geometric phase

Semimetal

Band gap

Quantum Hall effect

Berry connection and curvature

Acoustics

Condensed matter physics

Quantum anomalous Hall effect

Weyl semimetal

Lattice (music)

Thermal Hall effect

Fermion

Quantum mechanics

Electrical resistivity and conductivity

Ferromagnetism

Nature Physics

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 Kagomé lattices. This lattice provides an excellent platform for hosting exotic topological quantum states. We observe a negative magnetoresistance that is consistent with the chiral anomaly expected from the presence of Weyl nodes 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 Ω-1 cm-1 and 20%, respectively, an order of magnitude larger than typical magnetic systems. Combining the Kagomé-lattice structure and the 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.

Giant anomalous Hall effect in a ferromagnetic kagome-lattice semimetal