Weyl fermions with various chiralities in an f-electron ferromagnetic system: PrB₄

Rare-earth tetraborides (RB₄) have attracted a lot of recent attention due to their intriguing electronic, magnetic, and topological properties. We have theoretically investigated the topological properties of PrB₄, which is unique among the RB4 family due to its ferromagnetic ground state. We have discovered that PrB4 is an intrinsic magnetic Weyl system possessing multiple topological band crossings with various chiral charges. Density-functional-theory band calculations combined with a tight-binding band analysis reveal large Fermi-arc surface states, which are characteristic fingerprints of Weyl fermions. Anomalous Hall conductivity is estimated to be very large, ranging from 500 to 1000 (Ω cm)⁻¹ near the Fermi level, which also demonstrates the topological Weyl character of ferromagnetic PrB₄. These findings suggest that PrB₄, being a potential candidate of a magnetic Weyl system, would be a promising rare-earth topological system for applications to next-generation spintronic and photonic devices.