Magnetic properties of the layered magnetic topological insulator Eu Sn 2 As 2

$\mathrm{Eu}{\mathrm{Sn}}_{2}{\mathrm{As}}_{2}$ with a layered rhombohedral crystal structure is proposed to be a candidate for an intrinsic antiferromagnetic (AFM) topological insulator. Here, we have investigated systematic magnetoresistance (MR) and magnetization measurements on the high-quality $\mathrm{Eu}{\mathrm{Sn}}_{2}{\mathrm{As}}_{2}$ single crystal with the magnetic field both parallel and perpendicular to the (00l) plane. Both the kink of magnetic susceptibility and longitudinal resistivity reveal that $\mathrm{Eu}{\mathrm{Sn}}_{2}{\mathrm{An}}_{2}$ undergoes an AFM transition at ${T}_{\mathrm{N}}=21\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. At $T=2\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, the magnetization exhibits two successive plateaus of \ensuremath{\sim}5.6 and $\ensuremath{\sim}6.6\phantom{\rule{0.16em}{0ex}}{\ensuremath{\mu}}_{\mathrm{B}}/\mathrm{Eu}$ at the corresponding critical magnetic fields. Combined with the negative longitudinal MR and abnormal Hall resistance, we demonstrate that $\mathrm{Eu}{\mathrm{Sn}}_{2}{\mathrm{An}}_{2}$ undergoes complicated magnetic transitions from an AFM state to a canted ferromagnetic (FM) state at ${H}_{c}$ and then to a polarized FM state at ${H}_{s}$ as the magnetic field increases.