Physical Properties of Antiferromagnetic Dirac Semimetal SrMnSb _2

We have prepared high-quality nearly stoichiometric single crystal of Dirac semimetal SrMnSb _2 and systematically investigated the physical properties by measurements of magnetic susceptibility, heat capacity, electronic transport, and Hall effect. Magnetic and heat capacity measurements show that nearly stoichiometric SrMnSb _2 only undergoes an antiferromagnetic transition at T _N = 295 K and does not have any ferromagnetic component. The analysis of de Haas-van Alphen (dHvA) effect, Shubnikov-de Haas (SdH) effect, and Hall effect reveals that nearly stoichiometric SrMnSb _2 is a semimetal with multiple Fermi surfaces and linear dispersion. Furthermore, the nonsaturating linear magnetoresistance of SrMnSb _2 can be explained by the classical disorder theoretical model very well. Thus, the nonsaturating linear magnetoresistance of SrMnSb _2 is likely caused by both of linear dispersion and the classical disorder.