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Free keywords:
Charge density; Ground state; Monolayers; Photoelectron spectroscopy; Selenium compounds; Temperature; Titanium compounds, Angle resolved photoemission spectroscopy; Epitaxially grown; Low temperatures; Quantitative comparison; Structural aspects; Symmetry-breaking; Temperature dependent; Tight binding model, Charge density waves
Abstract:
We study the 2 × 2 charge density wave (CDW) in epitaxially-grown monolayer TiSe2. 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 TiSe2 in the 2D limit. © 2020 IOP Publishing Ltd
