Origin of magnetoelectric coupling effect and spin dynamics of multiferroic system Co4Nb2O9
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Date
2017-07-12
Journal Title
Journal ISSN
Volume Title
Publisher
International Conference on Neutron Scattering
Abstract
Co4Nb2O9,was recently reported to have large magnetoelectric coupling effect under a certain magnetic field. This compound has a crystal structure (space group P-3c1) derived from corundum structure and undergoes antiferromagnetic phase transition around 27K. It was previously believed that the magnetic moments of Co2+ order into a collinear antiferromagnetic structure in which magnetic moments are parallel to the c axis and form ferromagnetic chains with antiparallel inter-chain coupling. However, the recent study has shown that this magnetic structure model is incorrect. In this study, we found that the Co2+magnetic moments on both Co1 and Co2 sites align in the ab plane with a non-collinear configuration. Using inelastic neutron scattering, we measured the spin wave excitation from its magnetic phase along (h00) and (00l). A spin dynamic model proposed in this study is able to explain the observed spin dynamical behavior quite well. The nearest and next nearest neighbor interactions (NN and NNN) along the c axis are ferromagnetic. The interaction on the zig-zag ring of Co1 perpendicular to the c axis is highly frustrated while that of the zig-zag ring of Co2 is antiferromagnetic. The single ion anisotropy and Dzyaloshinskii-Moriya (DM) interaction contribute to the spin dynamics of Co4Nb2O9 as well. The simulated spin wave excitation by using SpinW[5] matches the experimental data very well. The DM interaction, which is most probably due to the triangle Co2-O-Co2 bond, was found to be the origin of the magnetoelectric coupling in this compound.
Description
Keywords
Electrical properties, Magnetic fields, Crystal structure, Antiferromagnetism, Magnetic moments, Phase transformations, Neutron diffraction, Spin
Citation
Deng, G., Cao, Y., Ren, W., Cao, S., Studer, A., Gauthier, N., Kenzelmann, M., Davison, G., Rule, K., Gardner, J. Imperia, P., Ulrich, C., & McIntyre, G. (2017). Origin of magnetoelectric coupling effect and spin dynamics of multiferroic system Co4Nb2O9. Paper presented at ICNS 2017 (International Conference on Neutron Scattering), Daejeon, South Korea, 9 to 13 July 2017. Retrieved from: http://www.icns2017.org/program.php