Angular dependence of interlayer magnetoresistance for antiferromagnetic dirac semimetal AMnBi₂ (A = Sr, Eu)

We report the results of comparative studies on angular dependent interlayer magnetoresistance (MR) in the presence of in-plane magnetic fields for layered Dirac antiferromagnets SrMnBi₂ and EuMnBi₂. For both materials, clear four-fold MR was observed at the lowest temperature as a manifestation of field-induced polarization of the anisotropic valleys. Interestingly, we have found a striking difference in angular dependence at high fields between SrMnBi₂ and EuMnBi₂. As a result of fitting to the empirical formula, we have revealed that EuMnBi₂ shows the anomalous field dependence of anisotropic factor, inconsistent with a simple semi-classical theory. We discuss the impact of Eu spins on the valley-selective interlayer conduction in EuMnBi₂. (author)