title: Temperature dependence of phonon modes in nanocrystalline La0.67ca0.33MnO3 as observed by infrared spectroscopy.
abstract: Low temperature infrared absorption measurements have been carried out on nanocrystalline La0.67Ca0.33MnO3 powder across the magnetic and the insulator-to-metal phase transitions. Interesting changes are observed in the temperature dependence of the mid-IR polaronic background and the stretching mode of the MnO, octahedron. Upon cooling below 250 K, the overall absorbance increases, but, unlike in the case of microcrystalline LCMO, the stretching mode is not completely screened even at 5 K. The temperature dependence of the stretching mode parameters points to a much reduced phonon-polaron coupling as compared to that in the bulk material.
authors.affiliation: Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, TN, India.
authors.forename: T N
authors.initials: TN
authors.lastname: Sairam
authors.forename: P
authors.initials: P
authors.lastname: Dey
authors.forename: G
authors.initials: G
authors.lastname: Mangamma
authors.forename: T K
authors.initials: TK
authors.lastname: Nath
authors.forename: C S
authors.initials: CS
authors.lastname: Sundar