超薄Cr₂Te₃膜表面におけるCr原子による半金属特性の誘起：第一原理計算による研究

Non-van der Waals layered transition metal chalcogenide Cr₂Te₃ exhibits unique properties including perpendicular magnetic anisotropy, anomalous Hall effect, and non-trivial band topology. Our first principles study further reveals that, induced by the surface Cr atoms, a transition from metallicity to a half-metallicity could occur when Cr2Te3 is reduced to an ultrathin film. The synergistic effect induced by the surface termination and the thickness of the film was found to play a crucial role in this transition. Specifically, a correlation between the bonding symmetry broken on the surface Cr, the strong orbital hybridization between surface Cr and Te atoms, and the squeeze of spin-down valence bands associated with Te-5p orbitals below the Fermi level was found in such ultra-thin 2D Cr2Te3 film during this transition. Such a finding provides key insights into the tunability of Cr₂Te₃ on its spintronic properties by modulating its thickness and surface termination, making it a potential application for designing highperformance spintronic devices.