Low Temperature Physics: 40, 58 (2014); https://doi.org/10.1063/1.4862464
Fizika Nizkikh Temperatur: Volume 40, Number 1 (January 2014), p. 75-82    ( to contents , go back )

Spin wave spectra and space-modulated structures in BiFeO3

A.F. Popkov1, N.E. Kulagin2, S.V. Soloviov1, Z.V. Gareeva3,4, and A.K. Zvezdin5,6,7

1Национальный исследовательский университет «МИЭТ» 4806 проезд, 5, Зеленоград, г. Москва, 124498, Россия

2Государственный университет управления, Рязанский пр., 99, г. Москва, 109542, Россия

3Upha Scientufic Centre Russian Academy of Sciences, Institute for Physics of Moleculs and Crystals 151, Octjabr` ave., Upha 450075, Russia

4Башкирский государственный университет, ул. З. Валиди, г. Уфа, 450076, Россия

5A.M. Prokhorov General Physics Institute of RAS, 38 Vavilov Str., Moscow 119991, Russia

6Московский физико-технический институт, г. Долгопрудный, Московская обл., Россия

7P.N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow 119991, Russia
E-mail: gzv@anrb.ru

Received Jule 8, 2013

Abstract

The spin wave spectrum in antiferromagnetic BiFeO3-type multiferroics is analyzed theoretically. It is shown that the presence of a space-modulated cycloidal structure leads to a countable number of branches of two types of frequency oscillations (Goldstone and activation modes) in the propagation of spin waves along the cycloid. In the absence of magnetic field and anisotropy the magnon spectrum is characterized by the lack of frequency gaps in the spectrum. The peculiarities of spectral dependences of spin oscillations on anisotropy and magnetic field are revealed and the limits of existence of the antiferromagnetic cycloid up to its transformation into a conical structure are determined. In the transverse direction the behavior of spin oscillations are of a mixed character, suggesting that the cycloid has bending stability in the whole area of its existence.

PACS: 75.30.Fv Spin-density waves;
PACS: 75.85.+t Magnetoelectric effects, multiferroics;
PACS: 75.50.Ee Antiferromagnetics;
PACS: 75.30.Gw Magnetic anisotropy;
PACS: 75.78.–n Magnetization dynamics.

Key words: spin waves, incommensurate structures, multiferroics, magnonic crystals.

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