We report two-dimensional quantum transport in SrMnBi$_2$ single crystals.The linear energy dispersion leads to the unusual nonsaturated linearmagnetoresistance since all Dirac fermions occupy the lowest Landau level inthe quantum limit. The transverse magnetoresistance exhibits a crossover at acritical field $B^*$ from semiclassical weak-field $B^2$ dependence to thehigh-field linear-field dependence. With increase in the temperature, thecritical field $B^*$ increases and the temperature dependence of $B^*$satisfies quadratic behavior which is attributed to the Landau level splittingof the linear energy dispersion. The effective magnetoresistant mobility$\mu_{MR}\sim 3400$ cm$^2$/Vs is derived. Angular dependent magnetoresistanceand quantum oscillations suggest dominant two-dimensional (2D) Fermi surfaces.Our results illustrate the dominant 2D Dirac fermion states in SrMnBi$_2$ andimply that bulk crystals with Bi square nets can be used to study lowdimensional electronic transport commonly found in 2D materials like graphene.
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机译：我们报告了SrMnBi $ _2 $单晶中的二维量子传输。线性能量色散导致异常的非饱和线性磁阻，因为所有Dirac费米子都占据了量子极限中的最低Landau能级。横向磁阻在临界场$ B ^ * $处从半经典弱场$ B ^ 2 $依赖关系到高场线性场依赖关系交叉。随着温度的升高，临界场$ B ^ * $增加，并且温度依赖性$ B ^ * $满足二次行为，这归因于线性能量色散的Landau能级分裂。推导出有效的磁阻迁移率\\ mu_ {MR} \ sim 3400 $ cm $ ^ 2 $ / Vs。依赖于角的磁阻和量子振荡表明存在二维（2D）费米表面，我们的结果说明了SrMnBi $ _2 $中占主导地位的2D Dirac费米子态，这表明具有Bi方形网的块状晶体可用于研究二维中常见的低维电子传输。石墨烯之类的材料。
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