Many-body effects in photoemission spectra of La1-xSrxCoO3

Abstract
Photoemission spectra of the system La1-xSrxCoO3 (0<or=x<or=0.5) have been measured. These deviate increasingly from those expected from a simple model as x rises, due to strong correlations between the holes in the system. The authors discuss the nature and origin of the many-body effects in the spectra, and show that they may to some extent be accounted for using a ladder approximation for the hole self-energy, once effects due to surface composition are included. They provide an estimate for the magnitude of the Hubbard U in this system.