Multiferroic hexagonal RMnO3 : a model system for 2D triangular lattice antiferromagnets
Jeudi 21 janvier 2016 14:00
- Duree : 1 heure
Lieu : ILL 4, Seminar Room, 71 avenue des Martyrs - Grenoble
Orateur : Je-Geun PARK (Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea - Department of Physics and Astronomy, Seoul National University, Seoul 151-747, 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] Hasung Sim, Joosung Oh, Jaehong, Jeong, Manh Duc Le, and Je-Geun Park Acta. Crystallog. B (in press) : arXiv:1511.04181
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