Raman scattering studies of spin‐waves in hexagonal BaFe12O19

Abstract

We present the results of polarized Raman spectroscopy of hexagonal BaFe12O19 single crystal. The spectra, recorded from 200 to 800 cm–1 and 1100 to 1700 cm–1 in the 20–250 K temperature range, are analyzed on the basis of both crystal vibrations and spin‐waves. In the low wavenumber range, the Γ‐point phonons are observed. In the high wavenumber range, phonon mixings are observed; more interestingly, four modes of spin‐waves are identified in hexagonal BaFe12O19. Both have not been studied previously. Our analyses of the spin‐waves provide an optical method for quantitatively estimating the spin exchange interactions in hexagonal BaFe12O19. The four strong exchange integrals are found to have the values of Jce = 1.31 meV, Jae = 1.36 meV, Jcd = 1.46 meV, and Jbd = 1.71 meV. Our results also indicate that at ~200 and ~80 K, there would be additional spin‐ordering transitions in hexagonal BaFe12O19. Copyright © 2012 John Wiley & Sons, Ltd.