Field dependence of the Spin State and Spectroscopic Modes of Multiferroic BiFeO${}_3$

Abstract

The spectroscopic modes of multiferroic BiFeO${}_3$ provide detailed information about the very small anisotropy and Dzyaloshinskii-Moriya (DM) interactions responsible for the long-wavelength, distorted cycloid below $\TN = 640$ K. A microscopic model that includes two DM interactions and easy-axis anisotropy predicts both the zero-field spectroscopic modes as well as their splitting and evolution in a magnetic field applied along a cubic axis. While only six modes are optically active in zero field, all modes at the cycloidal wavevector are activated by a magnetic field. The three magnetic domains of the cycloid are degenerate in zero field but one domain has lower energy than the other two in nonzero field. Measurements imply that the higher-energy domains are depopulated above about 6 T and have a maximum critical field of 16 T, below the critical field of 19 T for the lowest-energy domain. Despite the excellent agreement with the measured spectroscopic frequencies, some discrepancies with the measured spectroscopic intensities suggest that other weak interactions may be missing from the model.

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• Nonreciprocal Directional Dichroism and Toroidalmagnons in Helical Magnets
• Identifying the Magnetoelectric Modes of Multiferroic BiFeO${}_3$
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Cited by in corpus (10)

• Structure and spin dynamics of multiferroric BiFeO${}_3$
• Strain and Magnetic Field Induced Spin-Structure Transitions in Multiferroic BiFeO3
• Optical diode effect in the room-temperature multiferroic BiFeO$_3
• Spin and lattice excitations of a BiFeO3 thin film and ceramics
• Spin-Induced Polarizations and Non-Reciprocal Directional Dichroism of Multiferroic BiFeO${}_3$
• Reinforced magnetic properties of Ni-doped BiFeO3 ceramic
• The Microscopic Model of BiFeO${}_3$
• Pinning, Rotation, and Metastability of BiFeO${}_3$ Cycloidal Domains in a Magnetic Field
• Selection rules and dynamic magnetoelectric effect of the spin waves in multiferroic BiFeO${}_3$
• Orientation Dependence of the Critical Magnetic Field for Multiferroic BiFeO${}_3$