标题： 工程化超薄掺杂硫化铜中的金属-绝缘体转变 显示英文标题

标题： Engineering metal-insulator transitions in ultra-thin doped copper sulfides

摘要： 能带结构对于理解一种材料的电子行为至关重要。 由于电子、结构和组成因素之间复杂的相互作用，能带的精细调控仍然具有挑战性。 在这里，我们通过有效调节系统中铜和硫的成分来改变能带结构，展示了超薄硫化亚铜薄膜中形成不同的金属和绝缘基态。 利用角分辨光电子能谱（ARPES），我们在低温下观察到，在广泛的掺杂范围内，连续出现能带重归一化以及完整的能隙开启。 扫描隧道显微镜（STM）和低能电子衍射（LEED）测量支持了这种金属-绝缘体转变的电子起源，这些测量未显示出超晶格调制和晶格对称性破坏的迹象。 载流子密度相关的转变进一步提供了激子绝缘相存在的证据，这是电子屏蔽效应和库仑相互作用强度共同作用的结果。 我们的研究结果表明硫化亚铜能带结构的可调性，为研究奇异的量子相提供了新的机会。 显示英文摘要

摘要： Band structure is essential for understanding the electronic behavior of a material. The delicate engineering of the bands remains challenging because of the complex interplay of electronic, structural, and compositional factors. Here, we demonstrate the formation of distinct metallic and insulating ground states in ultra-thin copper sulfide films by effectively tuning the band structure via changing the composition of Cu and S in the system. Using angle-resolved photoemission spectroscopy (ARPES), we observed a continuous band renormalization and opening of a full gap at low temperatures over a wide range of doping. The electronic origin of this metal-insulator transition is supported by scanning tunneling microscopy (STM) and low energy electron diffraction (LEED) measurements, which show no indication of superlattice modulation and lattice symmetry breaking. The evidence of excitonic insulating phase is further provided by carrier density dependent transitions, a combined effect of electron screening and Coulomb interaction strength. Our findings demonstrate the tunability of the band structure of copper sulfides, allowing for new opportunities to study exotic quantum phases.