2D triangular lattice antiferromagnetism of multiferroic RMnO₃

Je-Geun Park^1,2
1 Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, Korea
² Department of Physics and Astronomy, Seoul National University, Seoul, Korea

Two-dimensional triangular lattice has been the source of rich physics with its generic frustration effects. We have investigated the spin-lattice coupling and magnetism of the two-dimensional triangular lattice in hexagonal RMnO₃. Hexagonal RMnO3 belongs to a class of multiferroic materials with both ferroelectric and antiferromagnetic transitions in a single compound. One of salient features of RMnO3 is that Mn ions form a natural 2D triangular lattice with a noncollinear 120° structure.
In this talk, I will present our works conducted over the past few years, where we have addressed mainly two issues: (i) the origin of magnetoelectric coupling and (ii) the spin waves. First, by using high-resolution neutron and synchrotron diffraction studies we demonstrated that a strong spin-lattice coupling lies at the heart of the magnetoelectric coupling in these compounds. Second, I will discuss how the spin waves measured by inelastic neutron scattering techniques allowed us to not only confirm the existence of a strong spin-lattice coupling but also unravel unusual nonlinear magnon interaction effects in these materials somewhat unexpectedly.

[1] Seongsu Lee, A. Pirogov, Misun Kang, Kwang-Hyun Jang, M. Yonemura, T. Kamiyama, S-W. Cheong, F. Gozzo, Namsu Shin, H. Kimura, Y. Noda, and J.-G. Park Nature 451, 805 (2008).
[2] Joosung Oh, Manh Duc Le, Jaehong Jeong, Jung-hyun Lee, Hyungje Woo, Wan-Young Song, T. G. Perring, W. J. L. Buyers, S-W. Cheong, and Je-Geun Park Phys. Rev. Lett. 111, 257202 (2013).
[3] [Invited Feature Article] Hasung Sim, Joosung Oh, Jaehong, Jeong, Manh Duc Le, and Je-Geun Park, Acta. Crystallog. B72, 3-19 (2016): arXiv:1511.04181

Back to Seminar Home Page

Last modified 22-February-2016 by website owner: NCNR (attn: )