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DOE OSTI · 1864424

Anisotropic spin-wave excitations in multiferroic BiFeO 3

Zhang, Depei·Dissanayake, Sachith·Winn, Barry·Matsuda, Masaaki·Ito, Toshimitsu·Fishman, Randy
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Abstract

Polarized inelastic neutron-scattering experiments have been performed to elucidate the anisotropic behavior of the low-energy spin-wave excitations in a multiferroic BiFeO 3 , which shows a cycloidal spin structure below 640 K. Using neutron polarization analysis for single magnetic domain crystals, magnetic excitation modes in and out of the cycloidal plane below 6 meV were separated successfully. The magnetic excitation spectra were analyzed using linear spin-wave theory. The low-energy magnon density of states consist of several magnon modes, including the two anisotropic modes, Φ and Ψ modes, distributed in and out of the cycloidal plane, respectively, which were previously observed using optical spectroscopies. Furthermore, there are other magnon modes that are not active in optical measurements. Additionally, a model spin Hamiltonian, which reproduces the spin-wave frequencies observed using optical spectroscopies, explains the overall spectra reasonably well.

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75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITYmagnetoelectric effectmultiferroicsneutron scatteringspin dynamics

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Zhang, Depei, Dissanayake, Sachith, Winn, Barry, Matsuda, Masaaki, Ito, Toshimitsu, Fishman, Randy. 2022-04-21. Anisotropic spin-wave excitations in multiferroic BiFeO 3. https://doi.org/10.1103/physrevb.105.144426

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