Lattice modulation expected for various types of spiral magnetic ordering with a propagation vector Qm is discussed in terms of the symmetric (Si·Sj type) and antisymmetric (Si x Sj type) exchange interactions between neighboring spins (S i and Sj). We show that the conical ordering causes the superlattice modulation with Qm via the antisymetric interaction, while the elliptical deformation of spiral induces a 2Qm modulation in lattice, due to the symmetric and antisymmetric interactions. This theoretical prediction was experimentally confirmed for a transverse elliptical antiferromagnet (Tb,Dy)MnO3 and a transverse conical ferrimagnet CoCr2O4, both accompanied by ferroelectricity (lattice deformation with Q = 0) as well.
|ジャーナル||journal of the physical society of japan|
|出版ステータス||Published - 2007 2月|
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