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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)
Author: Massa N.E.
Garcia-Flores A.F.
De Sousa Meneses D.
Del Campo L.
Echegut P.
Fabbris G.F.L.
Martinez-Lope M.J.
Alonso J.A.
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.
Rights: fechado
Identifier DOI: 10.1088/0953-8984/24/19/195901
Date Issue: 2012
Appears in Collections:Unicamp - Artigos e Outros Documentos

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