Proximity induced charge density wave in a graphene/1T-TaS<sub>2</sub> heterostructure.

Tilak, Nikhil; Altvater, Michael; Hung, Sheng-Hsiung; Won, Choong-Jae; Li, Guohong; Kaleem, Taha; Cheong, Sang-Wook; Chung, Chung-Hou et al. · Nat Commun · 2024

basic_science · Level V

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Abstract

The proximity-effect, whereby materials in contact appropriate each other's electronic-properties, is widely used to induce correlated states, such as superconductivity or magnetism, at heterostructure interfaces. Thus far however, demonstrating the existence of proximity-induced charge-density-waves (PI-CDW) proved challenging. This is due to competing effects, such as screening or co-tunneling into the parent material, that obscured its presence. Here we report the observation of a PI-CDW in a graphene layer contacted by a 1T-TaS<sub>2</sub> substrate. Using scanning tunneling microscopy (STM) and spectroscopy (STS) together with theoretical-modeling, we show that the coexistence of a CDW with a Mott-gap in 1T-TaS<sub>2</sub> coupled with the Dirac-dispersion of electrons in graphene, makes it possible to unambiguously demonstrate the PI-CDW by ruling out alternative interpretations. Furthermore, we find that the PI-CDW is accompanied by a reduction of the Mott gap in 1T-TaS<sub>2</sub> and show that the mechanism underlying the PI-CDW is well-described by short-range exchange-interactions that are distinctly different from previously observed proximity effects.