Short-range phase coherence and origin of the 1T-TiSe2 charge density wave

TL;DR

This study investigates how Ti self-doping influences the charge density wave in 1T-TiSe2, revealing that intercalated Ti atoms serve as nucleation centers for phase-shifted domains, linking domain size to the CDW phase transition.

Contribution

The paper demonstrates that Ti intercalation causes phase-shifted CDW domains and clarifies their role in the CDW phase transition in 1T-TiSe2, supported by microscopy and density functional theory.

Findings

Intercalated Ti atoms act as nucleation centers for CDW domains.

Domain size depends on Ti concentration.

CDW phase transition correlates with resistivity peak disappearance.

Abstract

The impact of variable Ti self-doping on the 1T-TiSe2 charge density wave (CDW) is studied by scanning tunneling microscopy. Supported by density functional theory we show that agglomeration of intercalated-Ti atoms acts as preferential nucleation centers for the CDW that breaks up in phaseshifted CDW domains whose size directly depends on the intercalated-Ti concentration and which are separated by atomically-sharp phase boundaries. The close relationship between the diminution of the CDW domain size and the disappearance of the anomalous peak in the temperature dependent resistivity allows to draw a coherent picture of the 1T-TiSe2 CDW phase transition and its relation to excitons.