Polaronic phase

Further evidence for phase segregation above and below Tc has been obtained with a variety of other techniques in addition to Mossbauer [ 117,118] and EXAFS [119]. In Lao.7Cao.3Mn03, Quijada et al. [122] have been able to describe the structure of the low-energy optical conductivity with a two-phase model. Kim et al. [ 123] came to a similar conclusion from their optical-conductivity data, and Zhao et al. [124] used pulsed laser excitation to reveal a fast transient associated with photoionization of the polaronic phase and a slow transient associated with the ferromagnetic phase in Lao.7Cao3Mn03. Sakaie et al. [125] have confirmed with La NMR a slow correlation time for the spin-spin fluctuations of the ferromagnetic clusters and reported an... 

Whereas we have proposed a phase segregation associated with a cross-over from the th > m Mn a polaronic phase to a th < ferromagnetic phase... 

Zhao et al. [145-147] were the first to show a dramatic decrease of Tc on the exchange of for If on cooling through Tc the transition was from a global polaronic phase with th > to a global itinerant-electron phase with Xh then the exchange of for 0, which decreases... 

---