Electronic structure and physical properties of EuAuAs single crystal

Abstract

High-quality single crystals of EuAuAs were studied by means of powder x-ray diffraction, magnetization, magnetic susceptibility, heat capacity, electrical resistivity and magnetoresistance measurements. The compound crystallizes with a hexagonal structure of the ZrSiBe type (space group $P{6}_{3}/mmc$). It orders antiferromagnetically below 6 K due to the magnetic moments of divalent Eu ions. The electrical resistivity exhibits metallic behavior down to 40 K, followed by a sharp increase at low temperatures. The magnetotransport isotherms show a distinct metamagneticlike transition in concert with the magnetization data. The antiferromagnetic ground state in EuAuAs was corroborated in the ab initio electronic band structure calculations. Most remarkably, the calculations revealed the presence of nodal line without spin-orbit coupling and Dirac point with inclusion of spin-orbit coupling. The $Z{}_{2}$ invariants under the effective time reversal and inversion symmetries make this system nontrivial topological material. Our findings, combined with experimental analysis, makes EuAuAs a plausible candidate for an antiferromagnetic topological nodal-line semimetal.