Effect of Ce doping on Raman-active crystal-field excitations in Nd2-xCexCuO4

Raman-active crystal-field (CF) excitations between the I-4(9/2) and I-4(11 /2) manifolds of Nd3+ in Nd2-xCexCuO4 have been studied as a function of th e cerium content x. With increasing x the main CF peaks become triplets. Th is indicates that the Nd3+ ions occupy sites with distinct local environmen ts where they experience different CFs. Changes in the relative intensities of the CF peaks with x. reflect the increasing perturbation of the system when cerium is introduced. The results show that CF Raman spectroscopy can be used, in addition to neutron scattering, as a local probe of doping-indu ced phenomena in high-temperature superconductors. (C) 1998 Elsevier Scienc e Ltd. All rights reserved.