부산대학교 도서관

While $d$-wave superconducting pairing symmetry dominates in cuprates, both $s$ and $d$ waves have been observed in infinite-layer nickelates. Understanding this novel difference is central to demystifying the similarities and distinctions between nickelates and cuprates. Here, by combining determinant quantum Monte Carlo with density-matrix renormalization group simulations in inhomogeneous Hubbard models, we discover that the charge-stripe period $\mathcal{P}$, differing in cuprates and nickelates, plays an unexpected role in determining the emergence of distinct pairing symmetries. Interestingly, while the $d$ wave is dominant for $\mathcal{P} \ge 4$, both (extended) $s$ and $d$ waves can appear when $\mathcal{P} \le 3$. Taking $\mathcal{P}=3$ as the case for nickelates, we discover that the interplay between the hole-doping concentration $\delta$ and charge-stripe amplitude $V_0$ can realize a novel $d$-$s$ wave transition. This interesting phenomenon originates from the charge-stripe-induced domain wall, which forms an unusual selection rule to generate $s$ and $d$ waves around the on-stripe region and inside the inter-stripe region, respectively, and gives rise to a critical point of $\mathcal{P}=3$ for the phase transition. Remarkably, during this transition, the $d$-wave state is transformed into a pairing-density wave state, competing with the $s$-wave state. Moreover, a novel magnetic-correlation transition accompanies the $d$-$s$ wave transition, indicating the inherent coupling between charge stripe, superconducting pairing, and magnetic correlation. In general, our unbiased simulations provide new insights into the difference in the superconducting pairing mechanism between nickelates and cuprates, highlighting the decisive role of charge stripe.
Comment: 5 figures, 9 pages with a supplement which including 15 figures. Much more data especially DMRG results are present