Raman Spectroscopy of Oriented / Epitaxial LaMnO3±δ Thin Films.

Manganite systems are known to exhibit a large number of phenomena. These compounds are highly correlated systems, i.e. there is a strong correlation present in various degrees of freedom like spin, charge, lattice and orbitals.  To understand various physical properties it is necessary to understand these correlation and Raman spectroscopy can be a very useful tool because it is sensitive to the local lattice distortion and symmetry of the specimen. In case of thin films it is more interesting to explore the behavior of various physical properties because other effects like thickness, strain imposed due to lattice mismatch between the substrate and thin films compounds affects the physical properties. In this presentation the behavior of Raman active modes across the phase transition temperature of LaMnO3±δ oriented/epitaxial thin films will be discussed. It will be shown that certain Raman active phonon modes are sensitive to the magnetic and metal-insulator transition temperature and they behave anomalously due to the strong spin-phonon coupling and strength of the Jahn-Teller distortion in the LaMnO3±δ thin films.