Epitaxial growth and characterization of few-layer 1T-NbSe2

Recently discovered ferromagnetic order in two-dimensional van der Waals crystals has attracted intense research. Spin ordering in these materials is carried by magnetic transition metal elements such as chromium. Here we demonstrate signatures of spin-ordered states in a strongly correlated 2D material: 1T-NbSe2. In contrast to the superconducting 2H-NbSe2 phase, strong electron correlation in 1T-NbSe2 gives rise to a Mott insulator phase. Stable 1T-NbSe2 can be grown under high temperatures in an ultra-high vacuum environment using molecular beam epitaxy (MBE). In this talk, we will present the epitaxial growth of high quality few-layer 1T-NbSe2 on the well-defined atomic terraces of a sapphire substrate. The sample crystal structure is confirmed by both x-ray diffraction (XRD) and in-situ reflection high energy electron diffraction (RHEED). The 1T-NbSe2 phase is further proved by X-ray photoelectron spectroscopy (XPS). Electrical transport studies of the grown samples revealed charge density wave (CDW) behavior. Spin density wave signatures are further captured via magnetotransport. Our work paves the way for investigating a wider range of spin ordered states such as antiferromagnetism in 2D materials.