The optical conductivity of La-Ca, Nd-Sr, and Bi-Sr manganites with commensurate charge order (CO) has been first observed in the sub-THz region. Below, the ordering temperature T(CO) well-defined peaks are observed, associated with side bands. They are assigned to pinned phasons, and to combinations of phasons and amplitudons, respectively. In La(1-n/8)Ca(n/8)MnO(3) with n = 5, 6, one can thus determine the electron-phonon coupling, the effective mass of the CO system, and its contribution to the dielectric constant. Their values support a description of the CO in La-Ca manganites in terms of a CDW approach. In Bi(0.5)Sr(0.5)MnO(3), where T(CO) > 500 K and the coupling is stronger, only the combination bands are clearly detected.
Sub-Terahertz Excitations in Manganites with Commensurate Charge Order / Nucara, Alessandro; Maselli, Paola; Calvani, Paolo; R., Sopracase; Ortolani, Michele; G., Gruener; M., Cestelli Guidi; U., Schade; J., Garcia. - In: JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM. - ISSN 1557-1939. - 22:1(2009), pp. 13-16. (Intervento presentato al convegno International Conference on Quantum Phenomena in Complex Matters tenutosi a Erice, ITALY nel JUL 26-AUG 01, 2008) [10.1007/s10948-008-0366-4].
Sub-Terahertz Excitations in Manganites with Commensurate Charge Order
NUCARA, Alessandro;MASELLI, Paola;CALVANI, Paolo;ORTOLANI, MICHELE;
2009
Abstract
The optical conductivity of La-Ca, Nd-Sr, and Bi-Sr manganites with commensurate charge order (CO) has been first observed in the sub-THz region. Below, the ordering temperature T(CO) well-defined peaks are observed, associated with side bands. They are assigned to pinned phasons, and to combinations of phasons and amplitudons, respectively. In La(1-n/8)Ca(n/8)MnO(3) with n = 5, 6, one can thus determine the electron-phonon coupling, the effective mass of the CO system, and its contribution to the dielectric constant. Their values support a description of the CO in La-Ca manganites in terms of a CDW approach. In Bi(0.5)Sr(0.5)MnO(3), where T(CO) > 500 K and the coupling is stronger, only the combination bands are clearly detected.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
