Strain induced phase separation on La0.5Ca0.5MnO3 thin films

Abstract The effect of epitaxial strain on La 0.5 Ca 0.5 MnO 3 films of various thicknesses grown on SrTiO 3 , SrLaAlO 4 , and SrLaGaO 4 substrates is studied by Raman spectroscopy, magnetic, and resistivity measurements. The transport and magnetic properties as well as Raman spectra of the films are affected by epitaxial strains. The energy of the A g (2) mode and the tilting angle of the MnO 6 octahedra is affected by the strain imposed by the substrate. In the spectra of the films deposited on the (1 0 0) SrTiO 3 substrate strong Jahn–Teller (JT) modes appear, which couple with charge-ordering. In all other films these modes are suppressed and no additional Raman lines are present at low temperatures contrary to the bulk compound. The low frequency continuum scattering decreases at low temperatures indicating a coupling with both the charge and orbital transitions. Comparison of the Raman spectra with the magneto-transport properties suggests an interpretation in terms of a strain induced phase separation between ferromagnetic metallic and antiferromagnetic insulating states.