Superconductivity in repulsively interacting fermions on a diamond chain: Flat-band-induced pairing

  title={Superconductivity in repulsively interacting fermions on a diamond chain: Flat-band-induced pairing},
  author={Keita Kobayashi and Masahiko Okumura and Susumu Yamada and Masahiko Machida and Hideo Aoki},
  journal={Physical Review B},
To explore whether a flat-band system can accommodate superconductivity, we consider repulsively interacting fermions on the diamond chain, a simplest quasi-one-dimensional system that contains a flat band. Exact diagonalization and the density-matrix renormalization group (DMRG) are used to show that we have a significant binding energy of a Cooper pair with a long-tailed pair-pair correlation in real space when the total band filling is slightly below $1/3$, where the dispersive band… 

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