Magnetism in Magnetic Weyl Semimetals

Weyl semimetals possess topological non-trivial bands that can give rise to exotic Fermi arcs and anomalous transport properties such as anomalous Hall and Nernst effects. By breaking time-reversal symmetry, magnetic Weyl semimetal is of particular interest because it provides an ideal platform to study the interplay between magnetism and band topology. I will first present our recently neutron & X-ray scattering study on the magnetic Weyl semimetal Mn 3 Sn. With polarized neutron diffraction, we determine the inverse triangular and non-coplanar magnetic structure of Mn 3 Sn in the commensurate and incommensurate phase, respectively. More importantly, we observe the charge density waves whose wave vectors located at the second harmonics of the magnetic peaks. The existence of charge density waves indicates strong coupling between magnetism and lattice, generating energy gap in the spin wave excitations observed in the inelastic neutron spectra. Our study calls further investigation into the nesting of Fermi surface in topological materials. For the second part, I would like talk about our progress on the VNb 3 S 6 , a magnetic Weyl semimetal metal candidate exhibits heavy fermion behavior and anomalous Hall effect. Complicated evolution of magnetic domains with in-plane field was proposed based on our neutron diffraction and Hall effect measurements. This invokes real space probes such as optical Kerr mapping to study the domains in transition metal dichalcogenides intercalated with 3d metals.