Impact of temperature-dependent local and global spin order in RMnO3 compounds for spin–phonon coupling and electromagnon activity

The orthorhombic rare-earth manganite compounds R MnO _3 show a global magnetic order for $T\lt {T}_{N}$ , and several representatives are multiferroic with a cycloidal spin ground state order for $T\lt {T}_{{\rm{cycl}}}\lt {T}_{N}\approx 40\,{\rm{K}}$ . We deduce from the temperature dependence of...

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Bibliographic Details
Main Authors: S Elsässer, M Schiebl, A A Mukhin, A M Balbashov, A Pimenov, J Geurts
Format: Article
Language:English
Published: IOP Publishing 2017-01-01
Series:New Journal of Physics
Subjects:
Online Access:https://doi.org/10.1088/1367-2630/aa55ed
Description
Summary:The orthorhombic rare-earth manganite compounds R MnO _3 show a global magnetic order for $T\lt {T}_{N}$ , and several representatives are multiferroic with a cycloidal spin ground state order for $T\lt {T}_{{\rm{cycl}}}\lt {T}_{N}\approx 40\,{\rm{K}}$ . We deduce from the temperature dependence of spin–phonon coupling in Raman spectroscopy for a series of R MnO _3 compounds that their spin order locally persists up to about twice T _N . Along the same line, our observation of the persistence of the electromagnon in GdMnO _3 up to $T\approx 100\,{\rm{K}}$ is attributed to a local cycloidal spin order for $T\gt {T}_{{\rm{cycl}}}$ , in contrast to the hitherto assumed incommensurate sinusoidal phase in the intermediate temperature range. The development of the magnetization pattern can be described in terms of an order–disorder transition at T _cycl within a pseudospin model of localized spin cycloids with opposite chirality.
ISSN:1367-2630