Phase engineering of atomically thin magnetic chromium tellurides via molecular beam epitaxy

Crystal structure engineering is pivotal for tailoring material properties, particularly in atomically thin two-dimensional (2D) transition-metal chalcogenides that exhibit rich, crystal-phase-dependent electronic, optical, and magnetic properties. However, their crystal-phase-controlled synthesis remains a critical challenge that limits their practical applications. Here, we report the phase-controlled synthesis of atomically thin chromium telluride films, including CrTe3, CrTe2, Cr1+δTe2, and CrTe, on graphene/SiC substrates via precise tuning of molecular beam epitaxy parameters. The growth mechanism is further revealed. We have systematically characterized the different structures and electronic, chemical, and magnetic properties of these films using scanning tunneling microscopy/spectroscopy, scanning transmission electron microscopy, density functional theory calculations, X-ray photoelectron/absorption spectroscopy, and circular-polarized X-ray photoemission electron microscopy. Heterostructures of different chromium telluride phases are further fabricated, demonstrating band engineering enabled by phase control of chromium tellurides. Researchers establish the growth phase diagram of atomically thin 2D CrxTey films by tuning MBE parameters, which is cross-validated by STEM and DFT calculations. XPS and XMCDPEEM are adopted to characterize the chemical and magnetic properties.