Long-wavelength magnetic and magnetoelectric excitations in the ferroelectric antiferromagnet BiFeO3

Abstract

We present a terahertz spectroscopic study of magnetic excitations in ferroelectric antiferromagnet BiFeO 3 . We interpret the observed spectrum of long-wavelength magnetic resonance modes in terms of the normal modes of the material's cycloidal antiferromagnetic structure. We find that the modulated Dzyaloshinski-Moriya interaction leads to a splitting of the out-of-plane resonance modes. We also assign one of the observed absorption lines to an electromagnon excitation that results from the magnetoelectric coupling between the ferroelectric polarization and the cycloidal magnetic structure of BiFeO 3 .

Spin-induced polarizations and nonreciprocal directional dichroism of the room-temperature multiferroicBiFeO3

“…By contrast, the frequencies of the spin-wave (SW) modes at the ordering wavevector Q can be precisely measured with Raman scattering 16 and THz spectroscopy 18,19 . The parameters K, D 1 , and D 2 were estimated by fitting the frequencies 27 of the four observed zero-field THz modes.…”

“…A great deal has been learned about BiFeO 3 since the first single crystals became available for inelastic neutron scattering [13][14][15] , Raman scattering 16,17 , and THz spectroscopy 18,19 measurements. It is now understood that two sets of interactions control the cycloid of BiFeO 3 : two Dzyaloshinskii-Moriya (DM) interactions produced by broken inversion symmetry and a single-ion anisotropy 20 (ANI) K along the direction of the FE polarization P FE .…”

Strain modulated transient photostriction in La and Nb codoped multiferroic BiFeO3 thin films

“…16 Talbayev et al used the terahertz spectroscopy to interpret the spectrum of long-wavelength magnetic resonance modes of BFO crystal. 17 Coupling of light with mechanical degrees of freedom in BFO was reported by Kundys et al, the light-induced wavelength dependent size change of BFO single crystal can be understood from photostriction effect, a superposition of photovoltaic effect and electrostrictive effect. 14,15 Although the photostriction effect has been found in BFO single crystal at room temperature, it remains intensive investigation aiming to understand the dynamical photostriction effect.…”

Giant Spin-Driven Ferroelectric Polarization inBiFeO3at Room Temperature

“…By contrast with type-II multiferroics, where T N ¼ T c and the ME polarizations have been well characterized [7], the large FE polarization, high Néel temperature, and long 62 nm period of BiFeO 3 have hindered measurement of its spin-driven ME polarization. Based on elastic [6,8] and inelastic neutron-scattering [9], Raman-scattering [10], and terahertz spectroscopy [11] measurements of recently available single crystals, it is now possible to provide detailed information about the intrinsic ME couplings in bulk BiFeO 3 . These results are crucial to control the electrical properties of BiFeO 3 with a magnetic field and vice versa.…”