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

The effect of epitaxial strain on La0.5Ca0.5MnO3 films of various thicknesses grown on SrTiO3, SrLaAlO4, and SrLaGaO4 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 Ag(2) mode and the tilting angle of the MnO6 octahedra is affected by the strain imposed by the substrate. In the spectra of the films deposited on the (1 0 0) SrTiO3 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.

Research highlights
► Controlling phase separation in manganites by strains.
► Different epitaxial strains from substrates induce different magnetotransport properties.
► The Raman spectra are strongly T-dependent and correlated with different phases.