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 emphasized in spite of apparent differences in the crystal structures and is explained by the same nearest surroundings of the Nd3+ ions in both compounds. This circumstance allows us to perform the crystal field calculation on 93 Stark levels coming from the two title compounds. In the fitting procedure a set of 20 free-ion and 9 crystal field phenomenological parameters is obtained with a mean deviation of 13.7 cm-1. Magnetic g-factors are computed from the derived wave functions. Exchange splittings of Nd3+ levels in a magnetically ordered state of Nd2BaCuO5 (TN=7.5 K) were measured. The experimentally obtained temperature dependence of the exchange splittings reveal quasi-onedimensional magnetic correlations that persist up to ~10 TN.