Crystal field effect on the f-levels of R1+xBa2-xCu3O6+delta (R = Sm, Nd)

Infrared (IR) spectroscopy has been used to observe the crystal field (CF) levels of the five lowest J multiplets of Sm3+ in regular D-4h symmetry sit es in Sm1+xBa2-xCu3O6+delta. From a fit to these levels., we have calculate d a set of the CF parameters. Doublet features in the IR spectra have been tentatively associated with the anisotropic Sm-Cu exchange interaction. The oretical analysis, using the superposition model, as well as density functi onal based ab initio calculations of the CF interaction have indicated that some of the IR bands arise from the Sm3+ ions occupying the C-4v symmetry Ba sites. The magnetic susceptibility of single-crystalline REBa2Cu3O6 (Re = Nd, Sm) has been measured and compared with calculations using the phenom enological CF parameters. (C) 2001 Elsevier Science B.V. All rights reserve d.