Superconductivity and Competing Orders in the Square-Lattice $t$-$J$-$V$ Model: Insights into Electron-Doped Cuprates

Kavli Affiliate: Fuchun Zhang

| First 5 Authors: Qianqian Chen, Lei Qiao, Fuchun Zhang, Zheng Zhu,

| Summary:

To understand the discrepancies between the experimental observations of the
weak or absent superconductivity in electron-doped cuprates and the
extraordinarily robust superconductivity in numerical results of the
$t$-$J$-type model, we investigate the role of inter-site electron interactions
by studying the $t$-$J$-$V$-type model on square lattices. Based on large-scale
density matrix renormalization group simulations, we identify successive phases
when varying the inter-site electron interactions from attraction to repulsion,
including phase separation, uniform $d$-wave superconductivity, and a
pseudogap-like phase featuring pronounced charge-density-wave,
spin-density-wave and superconductivity fluctuations. Within the uniform
superconducting phase in such a process, a gradual suppression of
quasi-long-range superconductivity order occurs, culminating in its ultimate
destruction under elevated inter-site repulsion. We further examine this trend
based on the slave boson mean-field analysis of the role of inter-site electron
interactions. Meanwhile, the decay of charge density correlations slows
slightly, hinting at a nuanced competition between charge density wave and
superconductivity. The subsequent emergence of the pseudogap-like phase
showcases the slight dominance of charge-density-wave fluctuations. Our study
contributes insights that are pertinent to electron-doped cuprates and sheds
light on possibilities to reconcile the theoretical and experimental findings.

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