Spectroscopic Investigation of Bandwidth Control Effects on the Mott-Hubbard State in Epitaxial RVO3 (R = La, Pr, Y) Thin Films

Abstract

We investigate the systematic evolution of the electronic structure in epitaxially strained RVO3 (R = La, Pr, Y) thin films grown on LaAlO3 substrates, focusing on how materials modification (R-site cation substitution) combined with strain engineering controls the correlated electronic phase. Using synchrotron-based resonant photoemission (RPES) and X-ray absorption spectroscopy (XAS), we achieve bandwidth tuning by varying the R-site cation, which systematically modifies the GdFeO3-type octahedral distortions under consistent compressive strain. The RPES study reveals a shift of the incoherent V 3d feature from 1.3 eV (La) to 1.6 eV (Y), indicating increased electron localization. The combined electronic structure analysis establishes that the on-site Coulomb interaction (U) remains smaller than the charge transfer energy (Δ) across the RVO3 series, confirming a Mott-Hubbard insulating ground state-a distinct behavior from its bulk counterpart. Although the strength of the correlation (U/W) in LaVO3 to YVO3 rises slightly (2.07 to 2.43), the bandwidth and crystal-field splitting have no monotonic trend, where the crystal-field energy of PrVO3 is higher (about 2.4 eV). This anomalous behavior is driven by the competitive interplay between chemical pressure and epitaxial strain. These findings establish a quantitative design rule for tuning the Mott-Hubbard electronic ground state in vanadate heterostructures, offering a pathway to engineer the electronic properties of strongly correlated oxides for functional device applications.