Infrared reflectivity spectra of manganite thin films grown on different substrates

Abstract

We have measured the reflectivity infrared (IR) spectra of R1-x Ca x MnO3 (R∈=∈La, Pr) manganite thin films grown on different substrates (SrTiO3 (STO), LaAlO3 (LAO) and SrLaGaO4 (SLGO)) manganites over a wide frequency (50-5000 cm-1) range. In the Far IR (FIR) region the substrates dominate over the manganite spectrum. However, the previously observed infrared active modes or mode pairs could be identified. In the mid-IR (MIR) region, a characteristic insulating gap at 700 cm-1 is always present for all thin film studied, which shows substrate and thickness dependence.