The phonon structure of antiferromagnetic Bi2 Fe4 O9 (space group Pbnm No. 55, TN 240 K) was studied theoretically by calculations of lattice dynamics and experimentally between 10 and 300 K by polarized Raman spectroscopy. Most of the 12 Ag +12 B1g +9 B2g +9 B3g Raman modes were unambiguously identified. Strong second-order scattering was observed for ab -plane-confined incident and scattered light polarizations. In addition to the phonon-scattering, broad Raman bands with typical characteristics of magnon scattering appear below TN. The magnon bands are analyzed on the basis of magnetic structure of Bi2 Fe4 O9 and attributed to two-magnon excitations. © 2010 The American Physical Society.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 5 Jan 2010|