Regensburg 2019 – wissenschaftliches Programm
TT 47.10: Vortrag
Mittwoch, 3. April 2019, 17:30–17:45, H23
Magnon spectrum of the noncollinear antiferromagnet Mn3Ge — •Aleksandr S. Sukhanov1,2, Ph. Bourges3, H. C. Walker4, M. S. Pavlovskii5, K. Manna1, C. Felser1, and D. S. Inosov2 — 1Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany — 2Institut für Festkörperphysik, TU Dresden, 01069 Dresden, Germany — 3Laboratoire Léon Brillouin, CEA-CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette, France — 4ISIS Facility, STFC, Rutherford Appleton Laboratory,Didcot, Oxfordshire OX11-0QX, United Kingdom — 5Kirensky Institute of Physics, 660036 Krasnoyarsk, Russia
We discuss the full spin-wave spectrum of the noncollinear antiferromagnet Mn3Ge obtained using neutron time-of-flight and triple-axis spectroscopy. The sublattice of magnetic ions in hexagonal Mn3Ge can be viewed as two adjacent kagome layers stacked along the crystallographic  axis. Below TN of 370 K the Mn atoms form the coplanar triangular 120∘ antiferromagnetic (AFM) order. Our measurements revealed a magnon mode with a spin-wave gap of 5 meV and a very steep anisotropic dispersion. The obtained spectra allows one to build an effective model of magnetic interactions in the system. We found two coupled magnon-phonon excitations seen in the vicinity of the zone center on the energies of 14 meV and 17.5 meV. We argue that this mixed excitations represent a strong magneto-elastic coupling in Mn3Ge.