Non-Hermitian Skin Effect Enhances Pairing Correlations in Moiré Hubbard Systems

Abstract

We show that the non-Hermitian skin effect (NHSE) can enhance pairing correlations in moiré Hubbard systems through a channel-selective mechanism: skin-induced localization amplifies the boundary density of states, strengthening local pairing tendencies within an intermediate ``golden window'' of non-reciprocity $γ\in[0.5,1.2]\,t$. Using exact diagonalization of the non-Hermitian Hubbard model on triangular lattices with open boundaries, we map the $(U,γ)$ phase diagram. The double occupancy $D(γ)$ exhibits non-monotonic behavior -- rising by up to 21\% then declining -- reflecting a competition between NHSE-enhanced boundary pairing and over-localization. A decomposition of the pairing susceptibility $χ_{\mathrm{SC}}$ on the $3\times3$ cluster reveals that the NHSE acts \emph{channel-selectively}: it enhances on-site pairing ($+21\%$) while simultaneously suppressing competing antiferromagnetic correlations (22\% reduction), so that the total pairing susceptibility, dominated by the on-site channel, grows by $+98\%$ on that cluster. These trends are corroborated by an independent non-Hermitian DMRG calculation and establish an enhancement of finite-cluster pairing correlations rather than trivial density redistribution. We do not claim long-range superconducting order. A BCS scaling estimate converts the same pairing-response signal into a dome-shaped $T_c(γ)$ fingerprint, suggesting an experimentally distinguishable response in coherent-drive versus reservoir-dominated moiré devices.