  The Weyl antiferromagnet Mn$_3$Sn has recently attracted significant
attention as it exhibits various useful functions such as large anomalous Hall
effect that are normally absent in antiferromagnets. Here we report the thin
film fabrication of the single phase of Mn$_3$Sn and the observation of the
large anomalous Hall effect at room temperature despite its vanishingly small
magnetization. Our work on the high-quality thin film growth of the Weyl
antiferromagnet paves the path for developing the antiferromagnetic
spintronics.
