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KR: Fachgruppe Kristallographie

KR 4: Multiferroics I (DF jointly with DS, KR, MA, TT)

KR 4.10: Vortrag

Mittwoch, 18. März 2015, 12:00–12:15, EB 107

Magon-phonon interactions in hexagonal multiferroic YMnO₃ — •Andreas Kreisel¹, Shantanu Mukherjee¹, Brian M. Andersen¹, Turi Schäffer¹, Sonja Holm¹, Kim Lefmann¹, Niels C.R. Momsen¹, Jacob Larsen², Amy Fennell³, Uwe Stuhr³, and Zahra Yamani⁴ — ¹Niels Bohr Institute, University of Copenhagen, Denmark — ²Institute of Physics, Technical University of Denmark — ³Laboratory of Neutron Scattering, Paul Scherrer Institute, Switzerland — ⁴Chalk River National Laboratory, Canada

The multiferroic material YMnO₃ is known to show a large spin lattice coupling such that the spin and lattice degrees of freedom influence various properties, as for example the thermal conductivity that is found to have an anomalous contribution. The magnetoelastic modes have been measured recently in neutron diffraction experiments and linked to certain spectral features in Raman signals. Starting from a Heisenberg model on a triangular lattice with single ion anisotropies, we investigate the spin-phonon coupling via the magnetostriction mechanism and derive a coupled magnon-phonon model valid in the entire Brillouin zone. Within a spin-wave approach, where the coupling yields a hybrid magnon-phonon mode, we calculate the dynamic structure factor and compare to recent experimental neutron results.