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|Type:||Artigo de periódico|
|Title:||Collective Phase-like Mode And The Role Of Lattice Distortions At T Nt C In Rmn 2o 5 (r=pr, Sm, Gd, Tb, Bi)|
De Sousa Meneses D.
Del Campo L.
|Abstract:||We report on electronic collective excitations in RMn 2O 5 (R=Pr, Sm, Gd, Tb) showing condensation starting at and below T NT C4050K. Their origin is understood as partial delocalized e g electron orbitals in the JahnTeller distortion of the pyramid dimer with strong hybridized Mn 3+O bonds. Our local probes, Raman, infrared, and x-ray absorption, back the conclusion that there is no structural phase transition at T NT C. Ferroelectricity is magnetically assisted by electron localization triggering lattice polarizability by unscreening. We have also found phonon hardening as the rare earth is sequentially replaced. This is understood as a consequence of lanthanide contraction. It is suggested that partially f-electron screened rare earth nuclei might be introducing a perturbation to e g electrons prone to delocalize as the superexchange interaction takes place. © 2012 IOP Publishing Ltd.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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