Correlation-tuned Fermi-arc topology in a Weyl ferromagnet

Electrons on Fermi arcs (FAs), a hallmark of Weyl semimetals, exhibit chiral transport harboring chiral anomaly, negative magnetoresistance, and Majorana zero modes. While FAs have been observed in TaAs and Co 3 Sn 2 S 2 , the manipulation of FAs has been rarely explored. Here, we use Co 3 Sn 2 S 2 to show that tuning electronic correlation provides an effective way to control the topology and connectivity of FAs. After achieving a good agreement with experimentally measured band structure by employing combined density functional theory and dynamical mean-field theory (DFT+DMFT) calculations, we show that the experimental charge dynamics are well reproduced by DFT+DMFT calculations but not DFT calculations. Electronic correlation renormalizes the bands around the Fermi level and modifies the energy and location of Weyl points and the resulting FAs. In particular, on the Co-terminated surface, DFT+DMFT and experiments show FAs connecting Weyl points in adjacent Brillouin zones, whereas DFT indicates intra-zone connectivity. We further show the evolution of FAs with correlation and reveal a topological change in the FAs on the Sn-terminated surface at a stronger correlation strength. Our study sheds new light on the experimental manipulation of FAs to improve the electronic properties of correlated Weyl semimetals.