  Electronic structure of pulsed laser deposited epitaxial LaVO3 (LVO) thin
film grown on LaAlO3 (001) (LAO) substrate, has been studied at room
temperature and at 130 K, which is below the structural (141 K) and magnetic
transition temperatures (143 K) of single crystal LVO. Significant modification
in spectral intensity, largely around the V 3d - O 2p hybridized region, is
observed in valence band spectrum (VBS) of LVO film at 130 K. Resonant
photoemission study at 130 K confirms the presence of charge transfer screened
3dnL (L: hole in the O 2p) final state along with the dominant 3dn-1 final
state at 1.5 eV binding energy in the valence band. On the contrary, in the
room temperature VBS dominant V 3d sates with only 3dn-1 kind final state is
accentuated. To understand this difference, density functional theory (DFT)
calculations are employed. The changes in crystal structure from room
temperature orthorhombic (O-LVO) to low temperature monoclinic (M-LVO) symmetry
leads to remarkable change in the electronic structure around the Fermi level,
including transition from direct to indirect nature of band gap. Our
calculations also confirm an enhanced O 2p character in the valence band edge
of M-LVO that is hybridized with V 3d. These results are further corroborated
with octahedral distortions associated with the structural transition.
