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 topological properties of PrB₄, which is unique among 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 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 magnetic Weyl system, would be a promising rare-earth topological system for applications to next-generation spintronic and photonic devices.