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|Type:||Artigo de periódico|
|Title:||Collective phase-like mode and the role of lattice distortions at T-N similar to T-C in RMn2O5 (R = Pr, Sm, Gd, Tb, Bi)|
del Campo, L
|Abstract:||We report on electronic collective excitations in RMn2O5 (R = Pr, Sm, Gd, Tb) showing condensation starting at and below similar to T-N similar to T-C similar to 40-50 K. Their origin is understood as partial delocalized e(g) electron orbitals in the Jahn-Teller distortion of the pyramid dimer with strong hybridized Mn3+-O bonds. Our local probes, Raman, infrared, and x-ray absorption, back the conclusion that there is no structural phase transition at T-N similar to T-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 eg electrons prone to delocalize as the superexchange interaction takes place.|
|Editor:||Iop Publishing Ltd|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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