Physics Research Seminar: Prof. Dong-Hee Kim

Welcome to a research seminar by Prof. Dong-Hee Kim from the Gwangju Institute of Science and Technology in South Korea!

Host: Sebastiano Peotta (Academy Research Fellow, QD group)

Title: Disordered flat-band superconductivity in the kagome Hubbard model

Abstract: 

We investigate the fate of the flat-band superconductivity in the attractive Hubbard model on the kagome lattices under disorder. We consider two types of disorder: the uncorrelated random onsite potential and the correlated disorder [Phys. Rev. B 98, 235109 (2018)] designed to preserve the flat band in the parent noninteracting Hamiltonian. Using the Bogoliubov-de Gennes mean-field and exact diagonalization calculations, we find that superconductivity is significantly more resilient to the flat-band preserving disorder compared to the uncorrelated random potential. As disorder increases, spatial inhomogeneity emerges in the pairing, and the superfluid weight is eventually suppressed, which agrees with the picture of the superconductor-insulator transition in the disordered Hubbard model. However, in the weak disorder regime, the geometric contribution of the superfluid weight remains robust with the flat-band preserving disorder, while a notable decay is observed with the random onsite potential.