Orbital Origin of Extremely Anisotropic Superconducting Gap in Nematic Phase of FeSe Superconductor

被引：86

作者：

Liu, Defa ^{[1
,3
]}

Li, Cong ^{[1
,2
]}

Huang, Jianwei ^{[1
,2
]}

Lei, Bin ^{[4
,5
]}

Wang, Le ^{[1
,2
]}

Wu, Xianxin ^{[6
]}

Shen, Bing ^{[1
,2
]}

Gao, Qiang ^{[1
,2
]}

Zhang, Yuxiao ^{[1
]}

Liu, Xu ^{[1
]}

Hu, Yong ^{[1
,2
]}

Xu, Yu ^{[1
,2
]}

Liang, Aiji ^{[1
]}

Liu, Jing ^{[1
,2
]}

Ai, Ping ^{[1
,2
]}

Zhao, Lin ^{[1
]}

He, Shaolong ^{[1
]}

Yu, Li ^{[1
]}

Liu, Guodong ^{[1
]}

Mao, Yiyuan ^{[1
,2
]}

Dong, Xiaoli ^{[1
]}

Jia, Xiaowen ^{[7
]}

Zhang, Fengfeng ^{[8
]}

Zhang, Shenjin ^{[8
]}

Yang, Feng ^{[8
]}

Wang, Zhimin ^{[8
]}

Peng, Qinjun ^{[8
]}

Shi, Youguo ^{[1
]}

Hu, Jiangping ^{[1
,2
,9
]}

Xiang, Tao ^{[1
,2
,9
]}

Chen, Xianhui ^{[4
,5
]}

Xu, Zuyan ^{[8
]}

Chen, Chuangtian ^{[8
]}

Zhou, X. J. ^{[1
,2
,9
]}

机构：

[1] Chinese Acad Sci, Beijing Natl Lab Condensed Matter Phys, Inst Phys, Beijing 100190, Peoples R China

[2] Univ Chinese Acad Sci, Beijing 100049, Peoples R China

[3] Max Planck Inst Microstruct Phys, Weinberg 2, D-06120 Halle, Germany

[4] Univ Sci & Technol China, Hefei Natl Lab Phys Sci Microscale, Hefei 230026, Anhui, Peoples R China

[5] Univ Sci & Technol China, Dept Phys, Hefei 230026, Anhui, Peoples R China

[6] Julius Maximilaians Univ Wurzburg, Inst Theoret Phys & Astrophys, D-97074 Wurzburg, Germany

[7] Mil Transportat Univ, Tianjin 300161, Peoples R China

[8] Chinese Acad Sci, Tech Inst Phys & Chem, Beijing 100190, Peoples R China

[9] Collaborat Innovat Ctr Quantum Matter, Beijing 100871, Peoples R China

来源：

PHYSICAL REVIEW X | 2018年 / 8卷 / 03期

基金：

中国国家自然科学基金;

关键词：

HIGH-TEMPERATURE SUPERCONDUCTIVITY; IRON; NODES; ORDER;

D O I：

10.1103/PhysRevX.8.031033

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

The iron-based superconductors are characterized by multiple-orbital physics where all the five Fe 3d orbitals get involved. The multiple-orbital nature gives rise to various novel phenomena like orbitalselective Mott transition, nematicity, and orbital fluctuation that provide a new route for realizing superconductivity. The complexity of multiple-orbital physics also requires us to disentangle the relationship between orbital, spin, and nematicity, and to identify dominant orbital ingredients that dictate superconductivity. The bulk FeSe superconductor provides an ideal platform to address these issues because of its simple crystal structure and unique coexistence of superconductivity and nematicity. However, the orbital nature of the low-energy electronic excitations and its relation to the superconducting gap remain controversial. Here, we report direct observation of the highly anisotropic Fermi surface and extremely anisotropic superconducting gap in the nematic state of the FeSe superconductor by high-resolution laser-based angle-resolved photoemission measurements. We find that the low-energy excitations of the entire hole pocket at the Brillouin zone center are dominated by the single d(xz) orbital. The superconducting gap exhibits an anticorrelation relation with the d(xz) spectral weight near the Fermi level; i.e., the gap size minimum (maximum) corresponds to the maximum (minimum) of the d(xz) spectral weight along the Fermi surface. These observations provide new insights in understanding the orbital origin of the extremely anisotropic superconducting gap in the FeSe superconductor and the relation between nematicity and superconductivity in the iron-based superconductors.

引用

页数：10

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