title: Evidence of orbital excitations in CaCu3Ti4O12 probed by Raman spectroscopy.
abstract: Raman scattering studies on CaCu(3)Ti(4)O(12) and SrCu(3)Ti(4)O(12) compounds provide evidence of the physics underlying the giant dielectric effect in the CaCu(3)Ti(4)O(12) compound. The temperature, polarization, and photon energy dependence of a broad Raman mode observed at high wavenumbers below ∼130 K indicates its origin from orbital excitations. The orbital order disorder transition observed around 100 K may be responsible for the conductivity changes required in the internal barrier layer capacitance model, hitherto used to explain the huge dielectric constant above 100 K in these compounds.
authors.affiliation: UGC-DAE Consortium for Scientific Research, University Campus, Indore 452017, India.
authors.forename: Dileep K
authors.initials: DK
authors.lastname: Mishra
authors.forename: V G
authors.initials: VG
authors.lastname: Sathe
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D017097:Electric Impedance; D008422:Materials Testing; D044367:Phase Transition; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D017610:Calcium Compounds