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arXiv · 1803.01041

Spin-wave induced phonon resonance in multiferroic BiFeO$_3$

Zhijun Xu·J. A. Schneeloch·Jinsheng Wen·M. Matsuda·D. Pajerowski·B. L. Winn·Yang Zhao·Christopher Stock·Peter M. Gehring·T. Ushiyama·Y. Yanagisawa·Y. Tomioka·T. Ito·Genda Gu·R. J. Birgeneau·Guangyong Xu
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Abstract

We report the direct observation of a "resonance" mode in the lowest-energy optic phonon very near the zone center around (111) in the multiferroic BiFeO$_3$ using neutron scattering methods. The phonon scattering intensity is enhanced when antiferromagnetic (AFM) order sets in at T$_N = 640$~K, and it increases on cooling. This "resonance" is confined to a very narrow region in energy-momentum space where no spin-wave excitation intensity is expected, and it can be modified by an external magnetic field. Our results suggest the existence of a novel coupling between the lattice and spin fluctuations in this multiferroic system in which the spin-wave excitations are mapped onto the lattice vibrations via the Dzyaloshinskii-Moriya (DM) interaction.

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Zhijun Xu, J. A. Schneeloch, Jinsheng Wen, M. Matsuda, D. Pajerowski, B. L. Winn, Yang Zhao, Christopher Stock, Peter M. Gehring, T. Ushiyama, Y. Yanagisawa, Y. Tomioka, T. Ito, Genda Gu, R. J. Birgeneau, Guangyong Xu. 2018-03-02. Spin-wave induced phonon resonance in multiferroic BiFeO$_3$. https://arxiv.org/abs/1803.01041

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