  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||c to P||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.
