Anomalous magneto-optical response near the ferromagnetic phase transition in Co₃Sn₂S₂

The magnetic Weyl semimetal candidate Co₃Sn₂S₂ hosts a kagome magnetic lattice and undergoes a ferromagnetic phase transition at T_c = 175K for the out-of-plane component of the magnetic moments. The Weyl physics hosted by Co₃Sn₂S₂ is known to be closely related to its magnetism, yet, the nature of its magnetism remains elusive. In this talk, we report an anomalous spike feature near Tc in the temperature dependent reflective magnetic circular dichroism (RMCD) response. This RMCD feature spans 2K about T_c and is corroborated by anomalous Hall measurements. We explore how this feature varies upon the excitation laser parameters, including power and repetition rate, image how it extends across real space, and examine its response across different thermocycles. We further discuss the role of the magnetic field on this feature and its connection to the ferromagnetic order below T_c.