Non-linear spin fluctuations and phase transitions in itinerant electron magnets: CMR manganites

We present a review analyzing the effects of coupling of transverse magnons with longitudinal spin fluctuations in isotropic itinerant ferro- and antiferromagnets. It is shown that this coupling essentially changes the spectrum of longitudinal fluctuations. At low-temperatures their spectrum is domi...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2012-10, Vol.324 (21), p.3613-3614
Main Authors: Solontsov, A., Antropov, V.P.
Format: Article
Language:English
Subjects:
Fluctuation
Formalism
Joining
Magnetic dynamics
Magnetic transitions
Magnetoresistance
Magnons
Manganites
Non-linear spin fluctuations
Nonlinearity
Phase transformations
Spin waves
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Summary:We present a review analyzing the effects of coupling of transverse magnons with longitudinal spin fluctuations in isotropic itinerant ferro- and antiferromagnets. It is shown that this coupling essentially changes the spectrum of longitudinal fluctuations. At low-temperatures their spectrum is dominated by the linear Landau relaxation, is purely quasielastic and described by a broad central peak of a paramagnon type. On approaching the critical temperature non-linear magnetic relaxation due to mode–mode couplings can dominate and lead to a rapid increase of the central peak and to a new mechanism of magnetic phase transitions governed by non-linear spin fluctuations. The formalism is applied to the CMR manganites where the observed quasielastic fluctuations can be viewed as non-linear spin-lattice fluctuations strongly affected by magnons.
ISSN:0304-8853
DOI:10.1016/j.jmmm.2012.02.103