  Weyl semimetals are new states of matter which feature novel Fermi arcs and
exotic transport phenomena. Based on first-principles calculations, we report
that the chalcopyrites CuTlSe2, AgTlTe2, AuTlTe2 and ZnPbAs2 are ideal Weyl
semimetals, having largely separated Weyl points (~ 0.05/A) and uncovered Fermi
arcs that are amenable to experimental detections. We also construct a minimal
effective model to capture the low-energy physics of this class of Weyl
semimetals. Our discovery is a major step toward a perfect playground of
intriguing Weyl semimetals and potential applications for low-power and
high-speed electronics.
