LAUSR

Ultrathin van der Waals (vdW) magnets are heavily pursued for potential applications in developing high‐density miniaturized electronic/spintronic devices as well as for topological physics in low‐dimensional structures. Despite the rapid advances in ultrathin ferromagnetic vdW magnets, the antiferromagnetic counterparts, as well as the antiferromagnetic junctions, are much less studied owing to the difficulties in both material fabrication and magnetism characterization. Ultrathin CrTe3 layers have been theoretically proposed to be a vdW antiferromagnetic semiconductor with intrinsic intralayer antiferromagnetism. Herein, the epitaxial growth of monolayer (ML) and bilayer CrTe3 on graphite surface is demonstrated. The structure, electronic and magnetic properties of the ML CrTe3 are characterized by combining scanning tunneling microscopy/spectroscopy and non‐contact atomic force microscopy and confirmed by density functional theory calculations. The CrTe3 MLs can be further utilized for the fabrication of a lateral heterojunction consisting of ML CrTe2 and ML CrTe3 with an atomically sharp and seamless interface. Since ML CrTe2 is a metallic vdW magnet, such a heterostructure presents the first in‐plane magnetic metal–semiconductor heterojunction made of two vdW materials. The successful fabrication of ultrathin antiferromagnetic CrTe3, as well as the magnetic heterojunction, will stimulate the development of miniaturized antiferromagnetic spintronic devices based on vdW materials.