arXiv:1308.4845 · Physical Review B
Superconductivity in the two-dimensional t - t′ -Hubbard model
Andreas Eberlein, Walter Metzner
Abstract
Using a recently developed renormalization group method for fermionic superfluids, we determine conditions for $d$-wave superconductivity in the ground state of the two-dimensional Hubbard model at moderate interaction strength, and we compute the pairing gap in the superconducting regime. A pairing instability signaled by a divergent flow in the Cooper channel leads to a superconducting state in all studied cases. The next-to-nearest-neighbor hopping ${t}^{\ensuremath{'}}$ plays a crucial role in the competition between antiferromagnetism and superconductivity. A sizable ${t}^{\ensuremath{'}}$ is necessary to obtain a sizable pairing gap.