B. Bohnenbuck

Absence of commensurate ordering at the polarization flop transition in multiferroic DyMnO3

Ferroelectric spiral magnets DyMnO3 and TbMnO3 show similar behavior of electric polarization in applied magnetic fields. Studies of the field dependence of lattice modulations on the contrary show a completely different picture. Whereas in TbMnO3 the polarization flop from P parallel to c to P parallel to a is accompanied by a sudden change from incommensurate to commensurate wave vector modulation, in DyMnO3 the wave vector varies continuously through the flop transition. This smooth behavior may be related to the giant magnetocapacitive effect observed in DyMnO3.

Magnetic-field-induced transitions in multiferroic TbMnO 3 probed by resonant and nonresonant x-ray diffraction

Multiferroic

Magnetic structure of RuSr2GdCu2O8 determined by resonant x-ray diffraction.

{\text{TbMnO}}_{3}

Spin-charge-lattice coupling near the metal-insulator transition in Ca3Ru2O7

is investigated using x-ray diffraction in high magnetic fields. Measurements on first- and second-harmonic structural reflections due to modulations induced by the Mn and Tb magnetic order are presented as function of temperature and field oriented along the

Magnetic Structure ofRuSr2GdCu2O8Determined by Resonant X-Ray Diffraction

a

Magnetic structure of RuSr

and

_2

b

GdCu

directions of the crystal. The relation to changes in ordering of the rare earth moments in applied field is discussed. Observations below

_2

{T}_{N}^{\text{Tb}}

O

without and with applied magnetic field point to a strong interaction of the rare earth order, the Mn moments, and the lattice. Also, the incommensurate to commensurate transition of the wave vector at the critical fields is discussed with respect to the Tb and Mn magnetic order, and a phase diagram on basis of these observations for magnetic fields