Pressure Driven Topological and Quantum Phase Transition on Magnetic Weyl Kagome Lattice*

Recently, the Shandite compound Co₃Sn₂S₂ has been proved as a magnetic Weyl semimetal[1-3]. Co₃Sn₂S₂ possesses the out-of-plane magnetic Kagome lattice formed by Co atoms, which dominates the behaviors of Weyl fermions in this system. In this work, we performed experiments and theoretical calculations under high pressures to study the evolution of the topological state in Co₃Sn₂S₂. Experimental results show that the Curie temperature, anomalous Hall conductivity, and coercitive force of Hall curves decrease with increasing pressure. The ordinary Hall coefficient changes sign at a critical pressure, producing a maximum of the carrier concentration and a switch of the carrier types. Around 40 GPa the magnetic order finally disappears and the system goes into the protection of time reversal symmetry, becoming a topological insulator phase above 40 GPa. The calculations further found that additional Weyl nodes emerge with increasing pressure, showing low- and high-pressure Weyl fermion states. The topological and quantum phase transition is observed under pressure in the magnetic Weyl semimetal Co₃Sn₂S₂.
1. E. K. Liu et al. Nat. Phys. 14, 1125 (2018).
2. D. F. Liu et al. Science 365, 1282 (2019).
3. N. Morali et al. Science 365, 1286 (2019).