CRYSTAL-FIELD RAMAN-SCATTERING IN ND2CUO4

Raman scattering involving transitions between the components of the g round I-4(9/2) and the excited I-4(11/2) multiplets of Nd3+ in Nd2CuO4 is reported. The energies and symmetries of all five I-4(9/2) and fiv e of the Six I-4(11/2) were determined. Direct Raman coupling to the c rystal field excitations occurs (contrary to NdBa2Cu3O7, where the cou pling occurs through phonon admixture), possibly because of the lack o f inversion symmetry of the Nd sites. At low temperatures a coupling w as observed between the crystal-field excitation near 119 cm-1 and a N d-vibration. Below 150 K the crystal-field excitations exhibit a tempe rature-independent splitting (3 - 5 cm-1), possibly related to the pre sence of two Nd atoms per primitive cell.