1Department of Physics, Zhejiang University, Hangzhou 310027 2Department of Applied Physics, China Jiliang University, Hangzhou 310018 3Department of Physics, Hangzhou Normal University, Hangzhou 310036 4Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093
Abstract：The measurements of magnetization, longitudinal and Hall resistivities are carried out on the intrinsic antiferromagnetic (AFM) topological insulator EuSn$_2$As$_2$. It is confirmed that our EuSn$_2$As$_2$ crystal is a heavily hole doping A-type AFM metal with the Néel temperature $T_{\rm N}$ = 24 K, with a metamagnetic transition from an AFM to a ferromagnetic (FM) phase occurring at a certain critical magnetic field for the different field orientations. Meanwhile, we also find that the carrier concentration does not change with the evolution of magnetic order, indicating that the weak interaction between the localized magnetic moments from Eu$^{2+}$ $4f^7$ orbits and the electronic states near the Fermi level. Although the quantum anomalous Hall effect (AHE) is not observed in our crystals, it is found that a relatively large negative magnetoresistance ($-$13%) emerges in the AFM phase, and exhibits an exponential dependence upon magnetic field, whose microscopic origin is waiting to be clarified in future research.
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2020, Vol. 37 
