Publication Type
Journal
Journal Name
Physical Review B
Publication Date
Page Number
220402
Volume
86
Issue
22
Abstract
We have identified three of the four magnetoelectric modes of multiferroic BiFeO3 measured using
THz spectroscopy. Excellent agreement with the observed peaks is obtained by including the effects
of easy-axis anisotropy along the direction of the electric polarization. By distorting the cycloidal
spin state, anisotropy splits the ±1 mode into peaks at 20 and 21.5 cm−1 and activates the lower
±2 mode at 27 cm−1 (T = 200 K). An electromagnon is identified with the upper ±1 mode at
21.5 cm−1. Our results also explain recent Raman and inelastic neutron-scattering measurements.
