Evidence for magnon-phonon coupling in the topological magnet Cu3 TeO6

We perform thermodynamic and inelastic neutron scattering (INS) measurements to study the lattice dynamics (phonons) of a cubic collinear antiferromagnet Cu3 TeO6 which hosts topological spin excitations (magnons). While the specific heat and thermal conductivity results show that the thermal transp...

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Bibliographic Details
Published in:Physical review. B 2020-06, Vol.101 (21)
Main Authors: Bao, Song, Cai, Zhengwei, Si, Wenda, Wang, Wei, Wang, Xiaomeng, Shangguan, Yanyan, Ma, Zhen, Dong, Zhao-Yang, Kajimoto, Ryoichi, Ikeuchi, Kazuhiko, Yu, Shun-Li, Sun, Jian, Li, Jian-Xin, Wen, Jinsheng
Format: Article
Language:English
Subjects:
Antiferromagnetism
Brillouin zones
Coupling
Cubic lattice
Dispersion
Excitation spectra
Heat conductivity
Heat transfer
Inelastic scattering
Magnons
Neutron scattering
Neutrons
Phonons
Polarons
Temperature
Thermal conductivity
Topology
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Summary:We perform thermodynamic and inelastic neutron scattering (INS) measurements to study the lattice dynamics (phonons) of a cubic collinear antiferromagnet Cu3 TeO6 which hosts topological spin excitations (magnons). While the specific heat and thermal conductivity results show that the thermal transport is dominated by phonons, the deviation of the thermal conductivity from a pure phononic model indicates that there is a strong coupling between magnons and phonons. In the INS measurements, we find a mode in the excitation spectra at 4.5 K, which exhibits a slight downward dispersion around the Brillouin zone center. This mode disappears above the Néel temperature and thus cannot be a phonon. Furthermore, the dispersion is distinct from that of a magnon. Instead, it can be explained by the magnon-polaron mode, collective excitations resulting from the hybridization between magnons and phonons. We consider the suppression of the thermal conductivity and emergence of the magnon-polaron mode to be evidence for magnon-phonon coupling in Cu3 TeO6.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.101.214419