Proximity induced charge density wave in a graphene/1T-TaS2 heterostructure

Nikhil Tilak; Michael Altvater; Sheng-Hsiung Hung; Choong-Jae Won; Guohong Li; Taha Kaleem; Sang-Wook Cheong; Chung-Hou Chung; Horng-Tay Jeng; Eva Y Andrei

doi:10.1038/s41467-024-51608-y

Proximity induced charge density wave in a graphene/1T-TaS₂ heterostructure

Nat Commun. 2024 Sep 14;15(1):8056. doi: 10.1038/s41467-024-51608-y.

Authors

Nikhil Tilak^#¹, Michael Altvater^#¹, Sheng-Hsiung Hung^#², Choong-Jae Won³, Guohong Li¹, Taha Kaleem¹, Sang-Wook Cheong¹, Chung-Hou Chung^{4

5

6}, Horng-Tay Jeng^{7

8

9}, Eva Y Andrei¹⁰

Affiliations

¹ Department of Physics and Astronomy, Rutgers, the State University of New Jersey, Piscataway, New Jersey, USA.
² Department of Physics, National Tsing Hua University, Hsinchu, Taiwan.
³ Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Department of Physics, Pohang University of Science and Technology, Pohang, Korea.
⁴ Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan. chung0523@nycu.edu.tw.
⁵ Physics Division, National Center for Theoretical Sciences, Taipei, Taiwan. chung0523@nycu.edu.tw.
⁶ Center for Theoretical and Computational Physics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan. chung0523@nycu.edu.tw.
⁷ Department of Physics, National Tsing Hua University, Hsinchu, Taiwan. jeng@phys.nthu.edu.tw.
⁸ Physics Division, National Center for Theoretical Sciences, Taipei, Taiwan. jeng@phys.nthu.edu.tw.
⁹ Institute of Physics, Academia Sinica, Taipei, Taiwan. jeng@phys.nthu.edu.tw.
¹⁰ Department of Physics and Astronomy, Rutgers, the State University of New Jersey, Piscataway, New Jersey, USA. eandrei@physics.rutgers.edu.

^# Contributed equally.

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-TaS₂ 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-TaS₂ 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-TaS₂ 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.

Abstract

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