Tuning of the charge ordered state in the manganite thin films by internal or external strains

We have investigated methods for tuning the charge ordered state in the R1–x Cax MnO3 (R = La, Pr) manganite thin films grown on different substrates (SrTiO3 (STO), LaAlO3 (LAO), SrLaGaO4 (SLGO) and SrLaAlO4 (SLAO)). We have studied thin films of the Pr1–x Cax MnO3 manganite under hydrostatic pressure for various doping levels in order to induce a delocalization of carriers and destroy the charge ordered state (CO). It appears that both doping and the strains from the substrate can alter the CO state and tune the electrical properties of the compound. We have also proved that the application of an external hydrostatic pressure induces similar spectral modifications to doping in the Pr1–x Cax MnO3 (LCMO) thin films. By our systematic Raman studies under varying external (temperature and pressure) and internal (interfacial strains and doping) conditions, we investigate certain modes and extract direct information about the amount of the Jahn–Teller (JT) distortions, the CO state, and the strain or pressure induced phase separation in the manganite thin films. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)