Magnetic and noncentrosymmetricWeyl fermion semimetals in the RAlGe family of compounds (R = rare earth)

Weyl semimetals are novel topological conductors that host Weyl fermions as emergent quasiparticles. In this Rapid Communication, we propose a new type ofWeyl semimetal state that breaks both time-reversal symmetry and inversion symmetry in the RAlGe (R = rare-earth) family. Compared to previous predictions of magnetic Weyl semimetal candidates, the prediction of Weyl nodes in RAlGe is more robust and less dependent on the details of the magnetism because the Weyl nodes are generated already by the inversion breaking and the ferromagnetism acts as a simple Zeeman coupling that shifts theWeyl nodes in k space. Moreover, RAlGe offers remarkable tunability, which covers all varieties ofWeyl semimetals including type I, type II, inversion breaking, and time-reversal breaking, depending on a suitable choice of the rare-earth elements. Furthermore, the unique noncentrosymmetric and ferromagnetic Weyl semimetal state in RAlGe enables the generation of spin currents.