Temperature-dependent photoluminescence in La2/3Ca1/3MnO3

Visible photoluminescence and its temperature dependence of La2/3Ca1/3MnO3 in the temperature range 138-293 K were measured. It was observed that the main broad band centered at similar to 1.77 eV with the shoulders at similar to 1.57 and similar to 1.90 eV existed in the entire temperature range. It can be well fitted by three Gaussian curves B-1, B-2 and B-3 centered at similar to 1.52, similar to 1.75 and similar to 1.92 eV, respectively. The intensities of the peak B-1 and B-2 vary as temperature increases. In the entire temperature range, the intensity of B-1 increases with increasing temperature, whereas that of B-2 decreases. The photoluminescence mechanisms for La2/3Ca1/3MnO3 are presented based on the electronic structures formed by the interactions among spin, charge and lattice, in which B-1 was identified with the charge transfer excitation of an electron from the lower Jahn-Teller split e(g) level of a Mn3+ ion to the e(g) level of an adjacent Mn4+ ion, B-2 is assigned to the transition between the spin up and spin down e(g) bands separated by Hund's coupling energy E-J and B-3 is attributed to the transition, determined by the crystal field energy E-C between a t(2g) core electron of Mn3+ to the spin up e(g) bands of Mn4+ by a dipole allowed charge transfer process. (C) 2004 Elsevier Ltd. All rights reserved.