M. Ramakrishnan, Y. Joly, Y.W. Windsor, L. Rettig, A. Alberca, E.M. Bothschafter, P. Lejay, R. Ballou, V. Simonet, V. Scagnoli, and U. Staub:
Phys. Rev. B 95, 205145 (2017), pp.10;
Chiral multiferroic langasites have attracted attention due to their doubly chiral magnetic ground state within an enantiomorphic crystal. We report on a detailed resonant soft x-ray diffraction study of the multiferroic Ba3TaFe3Si2O14 at the Fe L2,3 and oxygen K edges. Below TN (˜27K) we observe the satellite reflections (0,0,t), (0,0,2t), (0,0,3t), and (0,0,1-3t) where t˜0.140±0.001. The dependence of the scattering intensity on x-ray polarization and azimuthal angle indicate that the odd harmonics are dominated by the out-of-plane (ˆc axis) magnetic dipole while the (0,0,2t) originates from the electron density distortions accompanying magnetic order. We observe dissimilar energy dependencies of the diffraction intensity of the purely magnetic odd-harmonic satellites at the Fe L3 edge. Utilizing first-principles calculations, we show that this is a consequence of the loss of threefold crystal symmetry in the multiferroic phase.
The original publication is available by link DOI: 10.1103/PhysRevB.95.205145