Phase diagram of the square-lattice t−J−V model for electron-doped cuprates

Motivated by significant discrepancies between experimental observations of electron-doped cuprates and numerical results of the Hubbard and t-J models, we investigate the role of intersite interactions V by studying the t-J-V model on square lattices. Based on large-scale density matrix renormalization group simulations, we identify the ground-state phase diagram across varying intersite interactions V and doping concentration δ. We find that the phase diagram with finite intersite interactions 2V/J3 offers a more accurate description of electron-doped cuprates than the conventional Hubbard and t-J models. Moreover, we reveal the role of intersite interactions V at varying doping levels: at light doping, intersite interactions favor N\'eel antiferromagnetic order, and suppress both superconductivity and charge density wave; around optimal doping, these interactions support a pseudogap-like phase while suppressing superconductivity, and we further perform the slave-boson mean-field analysis to understand the numerical results microscopically; at higher doping, the effects of intersite interactions become insignificant, with our numerical predictions suggesting the emergence of an incommensurate spin density wave phase. Our specific focus around optimal doping with various intersite interactions identifies successive phases including phase separation, uniform d-wave SC, and a pseudogap-like phase, and reveals a relative insensitivity of the charge density wave to superconductivity. Our study suggests the t-J-V model as the minimal model to capture the essential physics of electron-doped cuprates.