中国物理B ›› 2021, Vol. 30 ›› Issue (6): 67401-067401.doi: 10.1088/1674-1056/abdea5
Feng Xu(徐峰)1,2,†, Lei Zhang(张磊)1,2, and Li-Yun Jiang(姜立运)1,2
Feng Xu(徐峰)1,2,†, Lei Zhang(张磊)1,2, and Li-Yun Jiang(姜立运)1,2
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.
中图分类号: (Theories and models of superconducting state)