Issue |
EPL
Volume 85, Number 5, March 2009
|
|
---|---|---|
Article Number | 57004 | |
Number of page(s) | 5 | |
Section | Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties | |
DOI | https://doi.org/10.1209/0295-5075/85/57004 | |
Published online | 20 March 2009 |
Dynamical magnetoelectric effects induced by the Dzyaloshinskii-Moriya interaction in multiferroics
Institut für Physik, Martin-Luther Universität Halle-Wittenberg - Heinrich-Damerow-Str.4 06120 Halle (Saale), Germany, EU
Received:
12
November
2008
Accepted:
13
February
2009
We study the dynamical interplay between ferroelectricity and
magnetism in a multiferroic with a helical magnetic order. We show that the
dynamical exchange-striction induces a biquadratic interaction between the spins and
transverse phonons resulting in quantum fluctuations of the spontaneous ferroelectric
polarization in the
ferroelectric phase. The hybridization between the spin wave and the fluctuation
of the electric polarization leads to low-lying transverse phonon modes. Those are
perpendicular to
and to the helical spins at small wave vector but then turn parallel to
at a wave vector close to the
magnetic modulation vector. For helical magnetic structure, the spin chirality which determines
the direction of
, also possesses
a long-range order. Due to the dynamical Dzyaloshiskii-Moriya interaction, the spin chirality
is strongly coupled to the spin fluctuation which implies an on-site inversion of the spin chirality in the ordered spin-(1/2) system and results in a finite scattering intensity
of polarized neutrons from a cycloidal helimagnet.
PACS: 75.80.+q – Magnetomechanical and magnetoelectric effects, magnetostriction / 71.70.Ej – Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect / 77.80.-e – Ferroelectricity and antiferroelectricity
© EPLA, 2009
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