Observation of charge-density-wave excitations in manganites.
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.
Nucara
A
A
CNR-INFM Coherentia and Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale A. Moro 2, I-00185 Roma, Italy.
Maselli
P
P
Calvani
P
P
Sopracase
R
R
Ortolani
M
M
Gruener
G
G
Guidi
M Cestelli
MC
Schade
U
U
García
J
J