Electron energy loss, x-ray photoemission and Auger spectroscopies have been used to study the valence states and the Cu 2p and O 1s core levels of YBa_2Cu_3O_7-delta as a function of the oxygen concentration delta. Evidence is found of dynamic charge fluctuations on the oxygen sublattice giving rise to a greater concentration of trivalent copper at the Cu(1) sites with respect to that determined by the analysis of neutron diffraction data. The lowest final states configurations of Cu2+ and Cu3+ are found to be c3d10L and c3d10L2, respectively, where c and L denote core holes on copper and oxygen atoms. Oxygen holes have high mobility and a Hubbard correlation energy less than 2 eV, a signature of their delocalization.
Balzarotti, A., DE CRESCENZI, M., Motta, N., Patella, F., Sgarlata, A. (1988). Electronic structure and charge fluctuations in YBa2Cu3O7 from EELS, XPS and Auger spectroscopies. INTERNATIONAL JOURNAL OF MODERN PHYSICS B, 1(5), 1135-1150 [10.1142/S0217979288001013].
Electronic structure and charge fluctuations in YBa2Cu3O7 from EELS, XPS and Auger spectroscopies
BALZAROTTI, ADALBERTO;DE CRESCENZI, MAURIZIO;PATELLA, FULVIA;SGARLATA, ANNA
1988-01-01
Abstract
Electron energy loss, x-ray photoemission and Auger spectroscopies have been used to study the valence states and the Cu 2p and O 1s core levels of YBa_2Cu_3O_7-delta as a function of the oxygen concentration delta. Evidence is found of dynamic charge fluctuations on the oxygen sublattice giving rise to a greater concentration of trivalent copper at the Cu(1) sites with respect to that determined by the analysis of neutron diffraction data. The lowest final states configurations of Cu2+ and Cu3+ are found to be c3d10L and c3d10L2, respectively, where c and L denote core holes on copper and oxygen atoms. Oxygen holes have high mobility and a Hubbard correlation energy less than 2 eV, a signature of their delocalization.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
