title: Observation of charge-density-wave excitations in manganites.
abstract: In the optical conductivity of four different manganites with commensurate charge order (CO), strong peaks appear in the meV range below the ordering temperature T_{CO}. They are similar to those reported for one-dimensional charge density waves (CDW) and are assigned to pinned phasons. The peaks and their overtones allow one to obtain, for La_{1-n/8}Ca_{n/8}MnO_{3} with n=5, 6, the electron-phonon coupling, the effective mass of the CO system, and its contribution to the dielectric constant. These results support a description of the CO in La-Ca manganites in terms of moderately weak coupling and of the CDW theory.
authors.affiliation: CNR-INFM Coherentia and Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale A. Moro 2, I-00185 Roma, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Nucara
authors.forename: P
authors.initials: P
authors.lastname: Maselli
authors.forename: P
authors.initials: P
authors.lastname: Calvani
authors.forename: R
authors.initials: R
authors.lastname: Sopracase
authors.forename: M
authors.initials: M
authors.lastname: Ortolani
authors.forename: G
authors.initials: G
authors.lastname: Gruener
authors.forename: M Cestelli
authors.initials: MC
authors.lastname: Guidi
authors.forename: U
authors.initials: U
authors.lastname: Schade
authors.forename: J
authors.initials: J
authors.lastname: García