Large linear magnetoresistance in a new Dirac material BaMnBi₂

Dirac semimetal is a class of materials that host Dirac fermions as emergent quasi-particles. Dirac cone-type band structure can bring interesting properties such as quantum linear magnetoresistance and large mobility in the materials. In this paper, we report the synthesis of high quality single crystals of BaMnBi₂ and investigate the transport properties of the samples. BaMnBi₂ is a metal with an antiferromagnetic transition at T _N = 288 K. The temperature dependence of magnetization displays different behavior from CaMnBi₂ and SrMnBi₂, which suggests the possible different magnetic structure of BaMnBi₂. The Hall data reveals electron-type carriers and a mobility μ (5 K) = 1500 cm²/V·s. Angle-dependent magnetoresistance reveals the quasi-two-dimensional (2D) Fermi surface in BaMnBi₂. A crossover from semiclassical MR ∼ H ² dependence in low field to MR ∼ H dependence in high field, which is attributed to the quantum limit of Dirac fermions, has been observed in magnetoresistance. Our results indicate the existence of Dirac fermions in BaMnBi₂. (rapid communication)