We study the 2 × 2 charge density wave (CDW) in epitaxially-grown monolayer TiSe 2 . Our temperature-dependent angle-resolved photoemission spectroscopy measurements indicate a strong-coupling instability, but reveal how not all states couple equally to the symmetry-breaking distortion, with an electron pocket persisting to low temperature as a non-bonding state. We further show how the CDW order can be suppressed by a modest doping of around 0.06(2) electrons per Ti. Our results provide an opportunity for quantitative comparison with a realistic tight-binding model, which emphasises a crucial role of structural aspects of the phase transition in understanding the hybridisation in the ground state. Together, our work provides a comprehensive understanding of the phenomenology of the CDW in TiSe 2 in the 2D limit.

中文翻译：

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单层TiSe 2中的强耦合电荷密度波

我们研究了外延生长的单层TiSe 2中的2×2电荷密度波（CDW）。我们依赖于温度的角度分辨光发射光谱测量结果显示出强耦合不稳定性，但揭示了并非所有状态如何均等地耦合到对称断裂畸变上，而电子囊却以非键合状态持续低温。我们进一步展示了如何通过每Ti约0.06（2）个电子的适度掺杂来抑制CDW阶。我们的结果提供了与现实的紧密结合模型进行定量比较的机会，该模型强调了相变结构方面在理解基态杂交中的关键作用。在一起，我们的工作提供了对TiSe 2中二维极限中CDW现象的全面理解。