Enhancement of Superconductivity by Isoelectronic Defects in The Fermi-Hubbard Ladder

In this work we show that superconductivity across a two-leg Fermi-Hubbard ladder can be enhanced by introducing changes of the hopping parameter at specific locations in each leg. Using density matrix renormalization group calculations, we obtain the ground state of the model with repulsive on-site interactions, open boundary conditions and below half filling. We find that modifying the hopping at the position of extremal values of the density Friedel oscillations can strongly increase the value of the superconducting correlations and Luttinger parameter, compared to the homogeneous case. We discuss the mechanism underlying this finding, and experimental platforms where it can be implemented. Our results provide a possible pathway to enhance the superconducting dome by disrupting the lattice structure without changing the number of charge carriers.