CHARGE-LOCALIZATION EFFECTS IN THE INFRARED TRANSMITTANCE OF LAYERED PEROVSKITES

In a previous study it has been shown that the formation of charged su perlattices in Ni-and Mn-based perovskites opens a gap in their infrar ed polaronic background. This signature of charge localization is here used to compare the behavior of the polaronic carriers in Sr2MnO4, La 2NiO4+y, Nd2CuO4-y and Nd1.85Ce0.15CuO4-y. It is shown that, as the te mperature decreases, the carriers tend to localize in the nickelate an d the manganite, to slightly increase their mobility in both cuprates. (C) 1998 Elsevier Science B.V. All rights reserved.