首页|Disentangling the electron-lattice dichotomy of the excitonic insulating phase in Ta2Ni(Se1-xSx)5 with sulfur substitution and potassium deposition

Disentangling the electron-lattice dichotomy of the excitonic insulating phase in Ta2Ni(Se1-xSx)5 with sulfur substitution and potassium deposition

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Disentangling the electron-lattice dichotomy of the excitonic insulating phase in Ta2Ni(Se1-xSx)5 with sulfur substitution and potassium deposition
Ta2NiSe5 is a promising candidate for hosting an excitonic insulator(EI)phase,a novel electronic state driven by electron-hole Coulomb attraction.However,the role of electron-lattice coupling in the formation of the EI phase remains controversial.Here,we use angle-resolved photoemission spectroscopy(ARPES)to study the band structure evolution of Ta2Ni(Se1-xSx)5 with sulfur substitution and potassium deposition,which modulate the band gap and the carrier concentration,respectively.We find that the Ta 5d states originating from the bottom of the conduction band persist at the top of the valence band in the low-temperature monoclinic phase,indicating the importance of exciton condensation in opening the gap in the semi-metallic band structure.We also observe that the characteristic overlap between the conduction and valence bands can be restored in the monoclinic lattice by mild carrier injection,suggesting that the lattice distortion in the monoclinic phase is not the main factor for producing the insulating gap,but rather the exciton condensation in the electronic system is the dominant driving force.Our results shed light on the electron-lattice decoupling and the origin of the EI phase in Ta2Ni(Se1-xSx)5.

excitonic insulatorangle-resolved photoemission spectroscopysulfur substitutionpotassium deposition

Tongrui Li、Yang Liu、Hongen Zhu、Haiping Chen、Zhanfeng Liu、Zhengming Shang、Yuiang Li、Hui Tian、Yunbo Wu、Yuhao Hong、Haihua Luo、Yi Liu、Guobin Zhang、Lidong Zhang、Yuqiao Guo、Changzheng Wu、Li Song、Shengtao Cui、Zhe Sun

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National Synchrotron Radiation Laboratory,University of Science and Technology of China,Hefei 230029,China

School of Chemistry and Materials Science,University of Science and Technology of China,Hefei 230026,China

School of Mechanics and Optoelectronic Physics,Anhui University of Science and Technology,Huainan 232001,China

CAS Key Laboratory of Strongly-coupled Quantum Matter Physics,University of Science and Technology of China,Hefei 230026,China

Collaborative Innovation Center of Advanced Microstructures,Nanjing 210093,China

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excitonic insulator angle-resolved photoemission spectroscopy sulfur substitution potassium deposition

2024

10.1007/s11433-024-2480-4

中国科学:物理学 力学 天文学(英文版)
中国科学院

中国科学:物理学 力学 天文学(英文版)

CSTPCD
影响因子：0.91
ISSN：1674-7348
年,卷(期)：2024.67(12)