Dynamical Dzyaloshinsky-Moriya Interaction in KCuF3
  The spin dynamics of the prototypical quasi one-dimensional antiferromagnetic Heisenberg spin S=1/2 chain KCuF3 is investigated by electron spin resonance spectroscopy. Our analysis shows that the peculiarities of the spin dynamics require a new dynamical form of the antisymmetric anisotropic spin-spin interaction. This dynamical Dzyaloshinsky-Moriya interaction is related to strong oscillations of the bridging fuorine ions perpendicular to the crystallographic c axis. This new mechanism allows to resolve consistently the controversies in observation of the magnetic and structural properties of this orbitally ordered perovskite compound. 
M. V. Eremin, D. V. Zakharov, H.-A. Krug von Nidda, R. M. Eremina, A.   Shuvaev, A. Pimenov, P. Ghigna, J. Deisenhofer, A. Loidl