High temperature superconductivity from kinetic energy

In this work, we propose a purely kinetic route towards high-temperature superconductivity. In conventional doped Mott insulators, pairing is restricted to small doping $x$, and thus the critical temperature is limited by the small phase stiffness. Here, we explore the possibility of pairing at large doping in a model with only nearest-neighbor hopping $t$ but projected into a constrained Hilbert space. Using density matrix renormalization group (DMRG) simulations on cylinders with Ly up to 8, we find that the ground state remains superconducting across the entire range of $x$. Notably, both the pairing gap and phase stiffness follow the Fermi energy even in the most overdoped region at $x = 0.5 $. Within the ideal model, we conclude that the optimal Tc is on the order of the hopping t. Above Tc, the system exhibits two different Fermi liquids on the $x\rightarrow0$ and $x\rightarrow1$ sides, whose Fermi surface volumes per flavor differ by half of the Brillouin zone. For specific parameters, the model has particle-hole symmetry, linking these two Fermi liquids. As a result, a symmetric Fermi liquid is forbidden in the Hilbert space at $x = 0.5$, and the superconductor cannot be viewed as a descendant of a Fermi liquid. Our model can be realized in the double Kondo lattice model relevant to the bilayer nickelate system, in the limit of infinite interlayer spin coupling $J_\perp/t \rightarrow +\infty $. We show that the superconductor smoothly connects to the more realistic regime with$J_\perp \sim t $, though the Tc may be reduced to the order of $ 0.1t $ rather than $t$. Given that $t \sim 10^3$K in typical solid-state systems, the material realization of the model may hold promise for achieving a $T_c$ on the order of hundreds of Kelvin.