Correlated electronic states of SrVO₃ revealed by angle-resolved photoemission spectroscopy

In this article, we review recent progress in angle-resolved photoemission (ARPES) studies of the Mott-Hubbard-type correlated electron systems SrVO₃. It has the d¹ electron configuration and is an ideal model compound to study electron correlation effects in normal metal. ARPES studies of bulk single-crystal SrVO₃ and CaVO₃ have revealed the difference in the mass renormalization of electrons between them. In-situ ARPES studies of thin films fabricated by the pulsed laser deposition method have clarified not only quasi-particle dispersions, which show a kink like high-T_c cuprates, but also finite dispersions in the incoherent part. Self-energy in a wide energy range has been deduced from the ARPES spectral weight using Kramers–Kronig transformation. The obtained self-energy has several structures which yield the incoherent feature and a pseudogap-like dip similar to the high-T_c cuprates. Quantum-well states in ultrathin films of SrVO₃ have revealed sub-bands with correlated electrons. These findings of electron correlation effects outlined in the present article would provide a starting point not only for fundamental condensed-matter physics but also for the development of new devices with correlated electrons.