Scrutinizing the double superconducting gaps and strong coupling pairing in (Li1-xFex)OHFeSe

Zengyi Du; Xiong Yang; Hai Lin; Delong Fang; Guan Du; Jie Xing; Huan Yang; Xiyu Zhu; Hai Hu Wen

doi:10.1038/ncomms10565

Scrutinizing the double superconducting gaps and strong coupling pairing in (Li_1-xFe_x)OHFeSe

Zengyi Du, Xiong Yang, Hai Lin, Delong Fang, Guan Du, Jie Xing, Huan Yang, Xiyu Zhu, Hai Hu Wen

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Abstract

In the field of iron-based superconductors, one of the frontier studies is about the pairing mechanism. The recently discovered (Li_1-xFe_x)OHFeSe superconductor with the transition temperature of about 40 K provides a good platform to check the origin of double superconducting gaps and high transition temperature in the monolayer FeSe thin film. Here we report a scanning tunnelling spectroscopy study on the (Li_1-xFe_x)OHFeSe single crystals. The tunnelling spectrum mimics that of the monolayer FeSe thin film and shows double gaps at about 14.3 and 8.6 meV. Further analysis based on the quasiparticle interference allows us to rule out the d-wave gap, and for the first time assign the larger (smaller) gap to the outer (inner) Fermi pockets (after folding) associating with the d_xy (d_xz/d_yz) orbitals, respectively. The gap ratio amounts to 8.7, which demonstrates the strong coupling mechanism in the present superconducting system.

Original language	English
Article number	10565
Journal	Nature Communications
Volume	7
DOIs	https://doi.org/10.1038/ncomms10565
State	Published - Jan 29 2016
Externally published	Yes

Funding

We acknowledge the useful discussions with Qianghua Wang, Jiangping Hu and Dun-ghai Lee. This work was supported by the National Natural Science Foundation of China (Grant No. 11534005, No.11190023), the Ministry of Science and Technology of China (973 projects: 2011CBA00100, 2012CB821403) and PAPD.

Funders	Funder number
National Natural Science Foundation of China	11190023, 11534005
Ministry of Science and Technology of the People's Republic of China	2011CBA00100, 2012CB821403
Priority Academic Program Development of Jiangsu Higher Education Institutions

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title = "Scrutinizing the double superconducting gaps and strong coupling pairing in (Li1-xFex)OHFeSe",

abstract = "In the field of iron-based superconductors, one of the frontier studies is about the pairing mechanism. The recently discovered (Li1-xFex)OHFeSe superconductor with the transition temperature of about 40 K provides a good platform to check the origin of double superconducting gaps and high transition temperature in the monolayer FeSe thin film. Here we report a scanning tunnelling spectroscopy study on the (Li1-xFex)OHFeSe single crystals. The tunnelling spectrum mimics that of the monolayer FeSe thin film and shows double gaps at about 14.3 and 8.6 meV. Further analysis based on the quasiparticle interference allows us to rule out the d-wave gap, and for the first time assign the larger (smaller) gap to the outer (inner) Fermi pockets (after folding) associating with the dxy (dxz/dyz) orbitals, respectively. The gap ratio amounts to 8.7, which demonstrates the strong coupling mechanism in the present superconducting system.",

author = "Zengyi Du and Xiong Yang and Hai Lin and Delong Fang and Guan Du and Jie Xing and Huan Yang and Xiyu Zhu and Wen, {Hai Hu}",

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AU - Du, Zengyi

AU - Yang, Xiong

AU - Lin, Hai

AU - Fang, Delong

AU - Du, Guan

AU - Xing, Jie

AU - Yang, Huan

AU - Zhu, Xiyu

AU - Wen, Hai Hu

PY - 2016/1/29

Y1 - 2016/1/29

N2 - In the field of iron-based superconductors, one of the frontier studies is about the pairing mechanism. The recently discovered (Li1-xFex)OHFeSe superconductor with the transition temperature of about 40 K provides a good platform to check the origin of double superconducting gaps and high transition temperature in the monolayer FeSe thin film. Here we report a scanning tunnelling spectroscopy study on the (Li1-xFex)OHFeSe single crystals. The tunnelling spectrum mimics that of the monolayer FeSe thin film and shows double gaps at about 14.3 and 8.6 meV. Further analysis based on the quasiparticle interference allows us to rule out the d-wave gap, and for the first time assign the larger (smaller) gap to the outer (inner) Fermi pockets (after folding) associating with the dxy (dxz/dyz) orbitals, respectively. The gap ratio amounts to 8.7, which demonstrates the strong coupling mechanism in the present superconducting system.

AB - In the field of iron-based superconductors, one of the frontier studies is about the pairing mechanism. The recently discovered (Li1-xFex)OHFeSe superconductor with the transition temperature of about 40 K provides a good platform to check the origin of double superconducting gaps and high transition temperature in the monolayer FeSe thin film. Here we report a scanning tunnelling spectroscopy study on the (Li1-xFex)OHFeSe single crystals. The tunnelling spectrum mimics that of the monolayer FeSe thin film and shows double gaps at about 14.3 and 8.6 meV. Further analysis based on the quasiparticle interference allows us to rule out the d-wave gap, and for the first time assign the larger (smaller) gap to the outer (inner) Fermi pockets (after folding) associating with the dxy (dxz/dyz) orbitals, respectively. The gap ratio amounts to 8.7, which demonstrates the strong coupling mechanism in the present superconducting system.

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Scrutinizing the double superconducting gaps and strong coupling pairing in (Li_1-xFe_x)OHFeSe

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