Flat band superconductivity in the attractive Hubbard model
일 시 : 2021년 12월 30일 목요일 16:00
연 사 : 김 지 철 박사 (광주과학기술원)
장 소 : 온라인 (줌 회의ID: 811 0183 4598 , 암호: 783734)
HOST : 신 상 진 교수님
초 록
Transport on a flat band would be ceased due to the non-existence of dispersion. On the other hand, the high density of states associated with the flat band would help form Cooper pairs that enable superconductivity. In the first part of my talk, I will review two particular previous efforts to understand these colliding features in a multiband system [1,2], where the authors decomposed the expression of the superfluid weight into two terms of different origins. One is the conventional contribution from the band dispersion, and the other is an unconventional one due to the quantum geometric effects, which turned out to be significant in the flat-band superconductivity. In the second part, I will introduce our ongoing numerical work on the superconductivity in the diluted attractive Hubbard model in the flat band systems of the kagome and Lieb lattices [3]. We address the questions of whether or not the flat-band superconductivity would survive with disorders and how the conventional and geometric terms of the superfluid weight change with the increasing disorder by using the mean-field theory, real-space dynamical mean-field theory, and exact diagonalization.
[1] S. Peotta and P. T¨orm¨a, Nat. Commun. 6, 8944 (2015).
[2] A. Julku, S. Peotta, T. I. Vanhala, D. -H. Kim, and P. T¨orm¨a, Phys. Rev. Lett. 117, 045303 (2016).
[3] J. Kim and D.-H. Kim, in preparation.