Janus effect of inter-orbital hybridization on correlation strength of strongly correlated systems: A dynamical mean-field study

In multi-orbital systems, the correlation strength is typically attributed to Coulomb interactions and Hund’s couplings. However, this study demonstrates that on-site inter-orbital hybridization can also significant influence the correlation strength of the system. We investigate the impact of on-site inter-orbital hybridization on the correlation strength of a two-orbital Hubbard model on a square lattice using the dynamical mean-field theory combined with Lanczos exact diagonalization. Our findings reveal a distinct Janus effect: on-site inter-orbital hybridization enhances correlation strength in the non-half-filled regime while suppresses it at half-filling. This dual role of on-site inter-orbital hybridization provides a fundamental mechanism for tuning the strength of correlations in multi-orbital systems.