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arXiv · 1806.00197

Suppression of Charge Density Wave by Substrate Induced Doping on TiSe$_2$/TiO$_2$ Heterostructure

Tao Jia·Slavko N. Rebec·Shujie Tang·Kejun Xu·Hafiz M. Sohail·Makoto Hashimoto·Dong-Hui Lu·Robert G. Moore·Zhi-Xun Shen
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Abstract

Substrate engineering provides an opportunity to modulate the physical properties of quantum materials in thin film form. Here we report that TiSe$_2$ thin films grown on TiO$_2$ have unexpectedly large electron doping that suppresses the charge density wave (CDW) order. This is dramatically different from either bulk single crystal TiSe$_2$ or TiSe$_2$ thin films on graphene. The epitaxial TiSe$_2$ thin films can be prepared on TiO$_2$ via molecular beam epitaxy (MBE) in two ways: by conventional co-deposition using selenium and titanium sources, and by evaporating only selenium on reconstructed TiO$_2$ surfaces. Both growth methods yield atomically flat thin films with similar physical properties. The electron doping and subsequent suppression of CDW order can be explained by selenium vacancies in the TiSe$_2$ film, which naturally occur when TiO$_2$ substrates are used. This is due to the stronger interfacial bonding that changes the ideal growth conditions. Our finding provides a way to tune the chemical potential of chalcogenide thin films via substrate selection and engineering.

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Tao Jia, Slavko N. Rebec, Shujie Tang, Kejun Xu, Hafiz M. Sohail, Makoto Hashimoto, Dong-Hui Lu, Robert G. Moore, Zhi-Xun Shen. 2018-06-01. Suppression of Charge Density Wave by Substrate Induced Doping on TiSe$_2$/TiO$_2$ Heterostructure. https://arxiv.org/abs/1806.00197

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