  Recently, MnBi2Te4 has been discovered as the first intrinsic
antiferromagnetic topological insulator (AFM TI), and will become a promising
material to discover exotic topological quantum phenomena. In this work, we
have realized the successful synthesis of high-quality MnBi2Te4 single crystals
by solid-state reactions. The as-grown MnBi2Te4 single crystal exhibits a van
der Waals layered structure, which is composed of septuple Te-Bi-Te-Mn-Te-Bi-Te
sequences as determined by powder X-ray diffraction (PXRD) and high-resolution
high-angle annular dark field scanning transmission electron microscopy
(HAADF-STEM). The magnetic order below 25 K as a consequence of A-type
antiferromagnetic interaction between Mn layers in the MnBi2Te4 crystal
suggests the unique interplay between antiferromagnetism and topological
quantum states. The transport measurements of MnBi2Te4 single crystals further
confirm its magnetic transition. Moreover, the unstable surface of MnBi2Te4,
which is found to be easily oxidized in air, deserves attention for onging
research on few-layer samples. This study on the first AFM TI of MnBi2Te4 will
guide the future research on other potential candidates in the MBixTey family
(M = Ni, V, Ti, etc.).
