Optical and crystal-field analysis of Nd3+ ion in Nd2BaCuO5 and Nd2BaZnO5

The absorption spectra of neodymium ion in the stoichiometric Nd2BaCuO5 and Nd2BaZnO5 compounds have been analyzed. The similarity of the spectra is e mphasized in spite of apparent differences in the crystal structures and is explained by the same nearest surroundings of the Nd3+ ions in both compou nds. This circumstance allows us to perform the crystal field calculation o n 93 Stark levels coming from the two title compounds. In the fitting proce dure a set of 20 free-ion and 9 crystal field phenomenological parameters i s obtained with a mean deviation of 13.7 cm(-1). Magnetic g-factors are com puted from the derived wave functions. Exchange splittings of Nd3+ levels i n a magnetically ordered state of Nd2BaCuO5 (T-N = 7.5 K) were measured. Th e experimentally obtained temperature dependence of the exchange splittings reveal quasi-one-dimensional magnetic correlations that persist up to simi lar to 10 T-N. (C) 2001 Academic Press.