Electronic structure of the band-filling-controlledCaVO3 andLaVO3 compounds

Abstract

We studied the electronic structure of the band-fillingCaVO3 andLaVO3 compounds. The experimental techniques were photoemission (PES)and x-ray absorption (XAS) spectroscopy. The experimental resultswere analyzed using an extended cluster model. The ground states ofCaVO3 andLaVO3 are highly covalent and contain a considerable3dn + 1L contribution.The CaVO3 compound is in the charge transfer regime (Δ < U), whereas theLaVO3 material is in theintermediate regime (Δ ∼ U). The spectral weight distributions reveal thatCaVO3 is a coherentmetal and that LaVO3 is a p–d insulator. The photoemission ofCaVO3 shows the coherent peak (3d1C) and the incoherent feature(3d1L). The spectrum ofinsulating LaVO3 presents onlythe incoherent structure (3d2L), whereas the coherent peak is replaced by the Mott–Hubbard screening (3d2D). This transfer of spectral weight is responsible for the opening of the experimentalbandgap. The incoherent feature contains a considerable O 2p character and cannot beattributed to the lower Hubbard band. Further, the relative V 3d–O 2p cross section helps toexplain the photon energy dependence of the PES spectra. The addition spectra of bothCaVO3 andLaVO3 are dominatedby the 3dn + 1 final state configuration. The distribution of spectral weight is mainly dictated byintra-atomic exchange and crystal field splittings. The coherent contribution is lessimportant than in photoemission, and is greatly diminished in the O 1s x-ray absorptionspectra.