中国物理B ›› 2021, Vol. 30 ›› Issue (6): 67401-067401.doi: 10.1088/1674-1056/abdea5

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Temperature and doping dependent flat-band superconductivity on the Lieb-lattice

Feng Xu(徐峰)1,2,†, Lei Zhang(张磊)1,2, and Li-Yun Jiang(姜立运)1,2   

  1. 1 School of Physics and Telecommunication Engineering, Shaanxi University of Technology, Hanzhong 723001, China;
    2 Institute of Graphene at Shaanxi Key Laboratory of Catalysis, Shaanxi University of technology, Hanzhong 723001, China
  • 收稿日期:2020-09-10 修回日期:2020-12-10 接受日期:2021-01-22 出版日期:2021-05-18 发布日期:2021-06-05
  • 通讯作者: Feng Xu E-mail:xufengxlx@snut.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 11804213), the Scientific Research Program Funded by Shaanxi Provincial Education Department (Grant No. 20JK0573), the Scientific Research Foundation of Shaanxi University of Technology (Grant No. SLGRCQD2006), and the Natural Science Basic Research Program of Shaanxi (Grant No. 2021JQ-748).

Temperature and doping dependent flat-band superconductivity on the Lieb-lattice

Feng Xu(徐峰)1,2,†, Lei Zhang(张磊)1,2, and Li-Yun Jiang(姜立运)1,2   

  1. 1 School of Physics and Telecommunication Engineering, Shaanxi University of Technology, Hanzhong 723001, China;
    2 Institute of Graphene at Shaanxi Key Laboratory of Catalysis, Shaanxi University of technology, Hanzhong 723001, China
  • Received:2020-09-10 Revised:2020-12-10 Accepted:2021-01-22 Online:2021-05-18 Published:2021-06-05
  • Contact: Feng Xu E-mail:xufengxlx@snut.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 11804213), the Scientific Research Program Funded by Shaanxi Provincial Education Department (Grant No. 20JK0573), the Scientific Research Foundation of Shaanxi University of Technology (Grant No. SLGRCQD2006), and the Natural Science Basic Research Program of Shaanxi (Grant No. 2021JQ-748).

摘要: We consider the superconducting properties of Lieb lattice, which produces a flat-band energy spectrum in the normal state under the strong electron-electron correlation. Firstly, we show the hole-doping dependent superconducting order amplitude with various electron-electron interaction strengths in the zero-temperature limit. Secondly, we obtain the superfluid weight and Berezinskii-Kosterlitz-Thouless (BKT) transition temperature with a lightly doping level. The large ratio between the gap-opening temperature and BKT transition temperature shows similar behavior to the pseudogap state in high-Tc superconductors. The BKT transition temperature versus doping level exhibits a dome-like shape in resemblance to the superconducting dome observed in the high-Tc superconductors. However, unlike the exponential dependence of Tc on the electron-electron interaction strength in the conventional high-Tc superconductors, the BKT transition temperature for a flat band system depends linearly on the electron-electron interaction strength. We also show the doping-dependent superconductivity on a lattice with the staggered hoping parameter in the end. Our predictions are amenable to verification in the ultracold atoms experiment and promote the understanding of the anomalous behavior of the superfluid weight in the high-Tc superconductors.

关键词: flat-band superconductivity, strong electron-electron interaction, superfluid weight, Berezinskii-Kosterlitz-Thouless (BKT) transition temperature

Abstract: We consider the superconducting properties of Lieb lattice, which produces a flat-band energy spectrum in the normal state under the strong electron-electron correlation. Firstly, we show the hole-doping dependent superconducting order amplitude with various electron-electron interaction strengths in the zero-temperature limit. Secondly, we obtain the superfluid weight and Berezinskii-Kosterlitz-Thouless (BKT) transition temperature with a lightly doping level. The large ratio between the gap-opening temperature and BKT transition temperature shows similar behavior to the pseudogap state in high-Tc superconductors. The BKT transition temperature versus doping level exhibits a dome-like shape in resemblance to the superconducting dome observed in the high-Tc superconductors. However, unlike the exponential dependence of Tc on the electron-electron interaction strength in the conventional high-Tc superconductors, the BKT transition temperature for a flat band system depends linearly on the electron-electron interaction strength. We also show the doping-dependent superconductivity on a lattice with the staggered hoping parameter in the end. Our predictions are amenable to verification in the ultracold atoms experiment and promote the understanding of the anomalous behavior of the superfluid weight in the high-Tc superconductors.

Key words: flat-band superconductivity, strong electron-electron interaction, superfluid weight, Berezinskii-Kosterlitz-Thouless (BKT) transition temperature

中图分类号:  (Theories and models of superconducting state)

  • 74.20.-z
74.20.Mn (Nonconventional mechanisms) 74.25.Bt (Thermodynamic properties)