Superconductivity and charge density wave in Cu0.06TiSe2: A low-temperature STM/STS investigation

2024-03-26

Xiaoqiu Yuan

Zongyuan Zhang

Yanwei Wu

Jian Yuan

Shuai Shao

Jie Hou

Yubing Tu

Xingyuan Hou

Gang Xu

Yanfeng Guo *

Lei Shan *

DOI：10.1063/5.0198934

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Abstract

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As one of the earliest discovered two-dimensional materials possessing charge density wave (CDW), TiSe2 has attracted wide attention due to its superconductivity induced by Cu intercalation. Until now, the relationship between superconductivity and CDW remains unclear, largely due to insufficient research at extremely low temperatures and magnetic fields. In this study, spatially resolved electronic density of states (DOS) of Cu0.06TiSe2 is investigated using low-temperature scanning tunneling microscopy/spectroscopy measurements. It is found that short-ranged commensurate CDW coexists with a homogeneous superconductivity exhibiting an anisotropic s-wave gap with an amplitude of 0.5 meV. Compared to the parent compound TiSe2, the spectra of Cu0.06TiSe2 exhibit a clear electron doping effect, as evidenced by a 70 meV shift of Fermi energy. Interestingly, the DOS is found to be strongly modified near the Fermi energy, despite its overall rigid band nature. These findings suggest that it is the remnant electron-hole coupling that sustains the short-ranged CDW, while the doping enhanced DOS facilitates superconductivity. This reveals a momentum space competition between the two microscopically coexistent orders.

Keywords:

MAGNETIC-PROPERTIES

TRANSITION

1T-TISE2

STATE

INHOMOGENEITY

TISE2

Superconductivity and charge density wave in Cu0.06TiSe2: A low-temperature STM/STS investigation

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