Optical properties and magnetochromism in multiferroic BiFeO3
Xu, X.S., T.V. Brinzari, S. Lee, Y.H. Chu, L.W. Martin, A. Kumar, S. McGill, R.C. Rai, Ramamoorthy Ramesh, V. Gopalan, S.W. Cheong, J.L. Musfeldt
In order to investigate spin-charge coupling in multiferroic oxides, we measured the optical properties of BiFeO3. Although the direct 300 K charge gap is observed at 2.67 eV, absorption onset actually occurs at much lower energy with Fe3+ excitations at 1.41 and 1.90 eV. Temperature and magnetic-field- induced spectral changes reveal complex interactions between on-site crystal-field and magnetic excitations in the form of magnon sidebands. We employ the sensitivity of these magnon sidebands to map out the magnetic-field-temperature phase diagram which demonstrates optical evidence for spin spiral quenching above 20 T and suggests a spin domain reorientation near 10 T. © 2009 The American Physical Society.
Physical Review B - Condensed Matter and Materials Physics
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