Twisted magnetic patterns: Exploring the Dzyaloshinskii--Moriya vector
  Magnetism - the spontaneous alignment of atomic moments in a material - is driven by quantum-mechanical `exchange' interactions which operate over atomic distances as a result of the fundamental symmetry of electrons. Currently, one of the most active fields of condensed matter physics involves the study of magnetic interactions that cause, or are caused by a twisting of nearby atoms. This can lead to the magnetoelectric effect that couples electric and magnetic properties, and is predicted to play a prominent role in future technology. Here, we discuss the complex relativistic interplay between magnetism and atomic crystal structure in a class of materials called `weak ferromagnets'. The sign of the underpinning Dzyaloshinskii--Moriya interaction has been determined for the first time, by using synchrotron radiation to study iron borate (FeBO3). We present a novel experimental technique based on interference between two x-ray scattering processes (one acts as a reference wave) which we combine with a second unusual approach of turning the atomic antiferromagnetic motif with a small magnetic field. We show that the experimental results provide a clear validation of state-of-the-art theoretical calculations. These experimental and theoretical approaches open up new possibilities for exploring, modelling and exploiting novel magnetic and magnetoelectric materials. 
V. E. Dmitrienko, E. N. Ovchinnikova, S. P. Collins, G. Nisbet, G.   Beutier, Y.O. Kvashnin, V. V. Mazurenko, A.I. Lichtenst...
cond-mat.str-el