Dresden 2020 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 38: Focus Session: Magnon Polarons – Magnon-Phonon Coupling and Spin Transport (joint session MA/HL)

HL 38.6: Hauptvortrag

Mittwoch, 18. März 2020, 11:45–12:15, HSZ 04

Magnon-polaron excitations in the noncollinear antiferromagnet Mn₃Ge — •Aleksandr Sukhanov — Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany

In this talk, the detailed inelastic neutron scattering measurements of the noncollinear antiferromagnet Mn₃Ge will be discussed. Time-of-flight and triple-axis spectroscopy experiments showed that the magnetic excitations in Mn₃Ge have a 5-meV gap and display an anisotropic dispersive mode reaching ≃ 90 meV at the boundaries of the magnetic Brillouin zone. The spectrum at the zone center shows two additional excitations that demonstrate characteristics of both magnons and phonons. The ab initio lattice-dynamics calculations show that these can be associated with the magnon-polaron modes resulting from the hybridization of the spin fluctuations and the low-energy optical phonons. The observed magnetoelastic coupling agrees with the previously found negative thermal expansion in this compound and resembles the features reported in the spectroscopic studies of other antiferromagnets with the similar noncollinear spin structures.