Bulk screening in core level photoemission from Mott-Hubbard and Charge-Transfer systems

Abstract

We report bulk-sensitive hard X-ray ($h\hat{I}½$ = 5.95 KeV) core level photoemission spectroscopy (PES) of single crystal V${}_{1.98}$Cr${}_{0.02}$O${}_3$ and the high-$T_c$ cuprate Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\hat{I}´}$ (Bi2212). V${}_{1.98}$Cr${}_{0.02}$O${}_3$ exhibits low binding energy "satellites" to the V $2p$ "main lines" in the metallic phase, which are suppressed in the antiferromagnetic insulator phase. In contrast, the Cu $2p$ spectra of Bi2212 do not show temperature dependent features, but a comparison with soft X-ray PES indicates a large increase in the $2p^{5}3d^9$ "satellites" or $3d^9$ weight in the bulk. Cluster model calculations, including full multiplet structure and a screening channel derived from the coherent band at the Fermi energy, give very satisfactory agreement with experiments.