%0 Journal Article
%A X.S Xu
%A T.V Brinzari
%A S Lee
%A Y.H Chu
%A L.W Martin
%A A Kumar
%A S McGill
%A R.C Rai
%A Ramamoorthy Ramesh
%A V Gopalan
%A S.W Cheong
%A J.L Musfeldt
%B Physical Review B - Condensed Matter and Materials Physics
%D 2009
%G eng
%R 10.1103/PhysRevB.79.134425
%T Optical properties and magnetochromism in multiferroic BiFeO3
%V 79
%X 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.