Yuki Tanaka, Rinsuke Yamada, Manabu Sato, Noriyuki Kabeya, Masaki Kondo, Noriaki Kimura, Masashi Tokunaga, Motoaki Hirayama, Max Hirschberger
Realization of a three-dimensional (3D) analog of graphene has been a central challenge in topological materials science. Graphene is stabilized by covalent bonding, unlike conventional spin-orbit-type 3D Dirac semimetals (DSMs). In this study, we demonstrate the material realization of covalent-type 3D DSMs R_{8}CoX_{3} stabilized by covalent bonding. We confirm the clean Dirac semimetal state in Y_{8}CoIn_{3} by combined thermodynamic and transport experiments. We also realize high carrier mobility exceeding 3000 cm^{2}/Vs even in polycrystalline samples of R_{8}CoX_{3}. Our research provides a material platform for exploration of Dirac electrons in three dimensions with wide chemical tunability.