Enhanced Weyl semimetal signature in Co3Sn2S2 Kagome ferromagnet by chlorine doping

Weyl fermions are chiral massless fermions with exotic properties. In the first established magnetic Weyl semimetal, Co3Sn2S2, a giant anomalous Hall effect has been observed, while its Fermi energy remaining 60 meV from the Weyl points. Shifting the Fermi energy closer to the Weyl points may assist in the identification of Weyl Fermion related transport signatures. Here we show that effective chlorine doping has resulted in a shift of the Fermi energy by 15 meV towards the Weyl points, which is confirmed by a combination of the systematic angular-resolved photoemission spectroscopy measurements and density function theory calculations. A five-fold reduction in resistivity is observed in the ferromagnetic phase, accompanied by a pronounced magnetoresistance of over 150%. The anomalous Hall conductivity shows a peak of 1680 Scm−1 at 40 K, which is 30% higher than the undoped sample due to a stronger Weyl point contribution. This work demonstrates the essential role of doping in Co3Sn2S2 for an enhanced Weyl semimetal signature. Weyl fermions are chiral massless fermions with interesting exotic properties. Here, chlorine doping of Co3Sn2S2 single crystals is found to shift the Fermi energy towards the Weyl points, enhancing its Weyl semimetal signatures such as a ninefold increase in magnetoresistance and a significantly larger anomalous Hall conductivity.