INFRARED STUDY OF CRYSTAL-FIELD EXCITATIONS IN ND2CUO4

We have observed infrared active Nd3+ ion crystal-field (CF) excitatio ns as a function of temperature in Nd2CuO4 single crystals. The detect ed absorption bands allowed to determine 23 excited CF levels of the 4 I term. Using these levels, a set of the parameters of the CF Hamilto nian has been calculated confirming the one determined previously by R aman measurements. CF excitations of Nd3+ ions, in inequivalent sites, have also been detected in as-grown single crystals and associated wi th two different types of defects. (C) 1998 Elsevier Science B.V. All rights reserved.