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1. Insulating Parent Phase and Distinct Doping Evolution to Superconductivity in Single-Layer FeSe/SrTiO3 Films

Author

Hu, Yong, Xu, Yu, Zhang, Yi-Min, Wang, Qing-Yan, He, Shao-Long, Liu, De-Fa, Liang, Ai-Ji, Huang, Jian-Wei, Li, Cong, Cai, Yong-Qing, Wu, Ding-Song, Liu, Guo-Dong, Fang-Sen, Fan, Jia-Qi, Zhou, Guan-Yu, Wang, Lili, Song, Can-Li, Ma, Xu-Cun, Xue, Qi-Kun, Xu, Zu-Yan, Zhao, Lin, and Zhou, X. J.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Materials Science, Condensed Matter - Strongly Correlated Electrons
Abstract

The single-layer FeSe/SrTiO3 (FeSe/STO) films have attracted much attention because of their simple crystal structure, distinct electronic structure and record high superconducting transition temperature (Tc). The origin of the dramatic Tc enhancement in single-layer FeSe/STO films and the dichotomy of superconductivity between single-layer and multiple-layer FeSe/STO films are still under debate. Here we report a comprehensive high resolution angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy measurements on the electronic structure evolution with doping in single-layer and multiple-layer FeSe/STO films. We find that the single-layer FeSe/STO films have a distinct parent phase and a route of doping evolution to superconductivity that are fundamentally different from multiple-layer FeSe/STO films. The parent phase of the single-layer FeSe/STO films is insulating, and its doping evolution is very similar to that of doping a Mott insulator in cuprate superconductors. In multiple-layer FeSe/STO films, high-Tc superconductivity occurs by suppressing the nematic order in the parent compound with electron doping. The single-layer FeSe/STO films represent the first clear case in the iron-based superconductors that the parent compound is an insulator. Our observations of the unique parent state and doping evolution in the single-layer FeSe/STO films provide key insight in understanding its record high-Tc superconductivity. They also provide a new route of realizing superconductivity in iron-based superconductors that is common in high temperature cuprate superconductors.

Published
2019
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2. Evidence of Electron-Hole Imbalance in WTe 2 from High-Resolution Angle-Resolved Photoemission Spectroscopy

Author

Wang, Chen-Lu, primary, Zhang, Yan, additional, Huang, Jian-Wei, additional, Liu, Guo-Dong, additional, Liang, Ai-Ji, additional, Zhang, Yu-Xiao, additional, Shen, Bing, additional, Liu, Jing, additional, Hu, Cheng, additional, Ding, Ying, additional, Liu, De-Fa, additional, Hu, Yong, additional, He, Shao-Long, additional, Zhao, Lin, additional, Yu, Li, additional, Hu, Jin, additional, Wei, Jiang, additional, Mao, Zhi-Qiang, additional, Shi, You-Guo, additional, Jia, Xiao-Wen, additional, Zhang, Feng-Feng, additional, Zhang, Shen-Jin, additional, Yang, Feng, additional, Wang, Zhi-Min, additional, Peng, Qin-Jun, additional, Xu, Zu-Yan, additional, Chen, Chuang-Tian, additional, and Zhou, Xing-Jiang, additional

Published
2017
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3. Common Electronic Features and Electronic Nematicity in Parent Compounds of Iron-Based Superconductors and FeSe/SrTiO 3 Films Revealed by Angle-Resolved Photoemission Spectroscopy

Author

Liu, De-Fa, primary, Zhao, Lin, additional, He, Shao-Long, additional, Hu, Yong, additional, Shen, Bing, additional, Huang, Jian-Wei, additional, Liang, Ai-Ji, additional, Xu, Yu, additional, Liu, Xu, additional, He, Jun-Feng, additional, Mou, Dai-Xiang, additional, Liu, Shan-Yu, additional, Liu, Hai-Yun, additional, Liu, Guo-Dong, additional, Zhang, Wen-Hao, additional, Li, Fang-Sen, additional, Ma, Xu-Cun, additional, Xue, Qi-Kun, additional, Chen, Xian-Hui, additional, Chen, Gen-Fu, additional, Yu, Li, additional, Zhang, Jun, additional, Xu, Zu-Yan, additional, Chen, Chuang-Tian, additional, and Zhou, Xing-Jiang, additional

Published
2016
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4. Electronic Structure of Transition Metal Dichalcogenides PdTe2 and Cu0.05PdTe2 Superconductors Obtained by Angle-Resolved Photoemission Spectroscopy

Author

Liu, Yan, Zhao, Jian Zhor, Yu, Li, Lin, Cheng Tian, Hu, Cheng, Liu, De Fa, Peng, Ying Ting, Xie, Zhuo Jin, He, Jun Feng, Chen, Chao Yu, Feng, Ya, Yi, He Mian, Liu, Xu, Zhao, Lin, He, Shao Long, Liu, Guo Dong, Dong, Xiao Li, Zhang, Jun, Chen, Chuang Tian, Xu, Zu Yan, Weng, Hongming, Dai, Xi, Fang, Zhong, Zhou, Xingjiang, Liu, Yan, Zhao, Jian Zhor, Yu, Li, Lin, Cheng Tian, Hu, Cheng, Liu, De Fa, Peng, Ying Ting, Xie, Zhuo Jin, He, Jun Feng, Chen, Chao Yu, Feng, Ya, Yi, He Mian, Liu, Xu, Zhao, Lin, He, Shao Long, Liu, Guo Dong, Dong, Xiao Li, Zhang, Jun, Chen, Chuang Tian, Xu, Zu Yan, Weng, Hongming, Dai, Xi, Fang, Zhong, and Zhou, Xingjiang

Abstract

The layered transition metal chalcogenides have been a fertile land in solid state physics for many decades. Various MX2-type transition metal dichalcogenides, such as WTe2, IrTe2, and MoS2, have triggered great attention recently, either for the discovery of novel phenomena or some extreme or exotic physical properties, or for their potential applications. PdTe2 is a superconductor in the class of transition metal dichalcogenides, and superconductivity is enhanced in its Cu-intercalated form, Cu0.05PdTe2. It is important to study the electronic structures of PdTe2 and its intercalated form in order to explore for new phenomena and physical properties and understand the related superconductivity enhancement mechanism. Here we report systematic high resolution angle-resolved photoemission (ARPES) studies on PdTe2 and Cu0.05PdTe2 single crystals, combined with the band structure calculations. We present in detail for the first time the complex multi-band Fermi surface topology and densely-arranged band structure of these compounds. By carefully examining the electronic structures of the two systems, we find that Cu-intercalation in PdTe2 results in electron-doping, which causes the band structure to shift downwards by nearly 16 me V in Cu0.05PdTe2. Our results lay a foundation for further exploration and investigation on PdTe2 and related superconductors. © 2015 Chinese Physical Society and IOP Publishing Ltd.

Published
2015

5. Electronic structure of transition metal dichalcogenides PdTe 2 and Cu 0.05 PdTe 2 superconductors obtained by angle-resolved photoemission spectroscopy

Author

Liu, Yan, primary, Zhao, Jian-Zhou, additional, Yu, Li, additional, Lin, Cheng-Tian, additional, Hu, Cheng, additional, Liu, De-Fa, additional, Peng, Ying-Ying, additional, Xie, Zhuo-Jin, additional, He, Jun-Feng, additional, Chen, Chao-Yu, additional, Feng, Ya, additional, Yi, He-Mian, additional, Liu, Xu, additional, Zhao, Lin, additional, He, Shao-Long, additional, Liu, Guo-Dong, additional, Dong, Xiao-Li, additional, Zhang, Jun, additional, Chen, Chuang-Tian, additional, Xu, Zu-Yan, additional, Weng, Hong-Ming, additional, Dai, Xi, additional, Fang, Zhong, additional, and Zhou, Xing-Jiang, additional

Published
2015
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6. Observation of a Flat Band in Silicene

Author

Feng, Ya, primary, Feng, Bao-Jie, additional, Xie, Zhuo-Jin, additional, Li, Wen-Bin, additional, Liu, Xu, additional, Liu, De-Fa, additional, Zhao, Lin, additional, Chen, Lan, additional, Zhou, Xing-Jiang, additional, and Wu, Ke-Hui, additional

Published
2014
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7. Fermi Surface and Band Structure of (Ca,La)FeAs 2 Superconductor from Angle-Resolved Photoemission Spectroscopy

Author

Liu, Xu, primary, Liu, De-Fa, additional, Zhao, Lin, additional, Guo, Qi, additional, Mu, Qing-Ge, additional, Chen, Dong-Yun, additional, Shen, Bing, additional, Yi, He-Mian, additional, Huang, Jian-Wei, additional, He, Jun-Feng, additional, Peng, Ying-Ying, additional, Liu, Yan, additional, He, Shao-Long, additional, Liu, Guo-Dong, additional, Dong, Xiao-Li, additional, Zhang, Jun, additional, Chen, Chuang-Tian, additional, Xu, Zu-Yan, additional, Ren, Zhi-An, additional, and Zhou, Xing-Jiang, additional

Published
2013
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8. Electronic structure of transition metal dichalcogenides PdTe2 and Cu0.05PdTe2 superconductors obtained by angle-resolved photoemission spectroscopy.

Author

Liu Yan, Zhao Jian-Zhou, Yu Li, Lin Cheng-Tian, Hu Cheng, Liu De-Fa, Peng Ying-Ying, Xie Zhuo-Jin, He Jun-Feng, Chen Chao-Yu, Feng Ya, Yi He-Mian, Liu Xu, Zhao Lin, He Shao-Long, Liu Guo-Dong, Dong Xiao-Li, Zhang Jun, Chen Chuang-Tian, and Xu Zu-Yan

Subjects
CHALCOGENIDES, SOLID state physics, PHOTOEMISSION, FERMI surfaces, QUANTUM statistics, TOPOLOGY
Abstract

The layered transition metal chalcogenides have been a fertile land in solid state physics for many decades. Various MX2-type transition metal dichalcogenides, such as WTe2, IrTe2, and MoS2, have triggered great attention recently, either for the discovery of novel phenomena or some extreme or exotic physical properties, or for their potential applications. PdTe2 is a superconductor in the class of transition metal dichalcogenides, and superconductivity is enhanced in its Cu-intercalated form, Cu0.05PdTe2. It is important to study the electronic structures of PdTe2 and its intercalated form in order to explore for new phenomena and physical properties and understand the related superconductivity enhancement mechanism. Here we report systematic high resolution angle-resolved photoemission (ARPES) studies on PdTe2 and Cu0.05PdTe2 single crystals, combined with the band structure calculations. We present in detail for the first time the complex multi-band Fermi surface topology and densely-arranged band structure of these compounds. By carefully examining the electronic structures of the two systems, we find that Cu-intercalation in PdTe2 results in electron-doping, which causes the band structure to shift downwards by nearly 16 meV in Cu0.05PdTe2. Our results lay a foundation for further exploration and investigation on PdTe2 and related superconductors. [ABSTRACT FROM AUTHOR]

Published
2015
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