Low Temperature Physics: 40, 134 (2014); https://doi.org/10.1063/1.4865560
Физика Низких Температур: Том 40, Выпуск 2 (Февраль 2014), c. 173-186    ( к оглавлению , назад )

One-magnon and exciton inelastic light scattering in the antiferromagnet CoF2

E. Meloche and M.G. Cottam

Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7, Canada

D.J. Lockwood

Institute for Microstructural Sciences, National Research Council, Ottawa, Ontario K1A 0R6, Canada
E-mail: David.Lockwood@nrc-cnrc.gc.ca

Received July 5, 2013


Experimental data are reported for the temperature and polarization dependence of the one-magnon Raman light scattering in the rutile-structure antiferromagnet CoF2 (Néel temperature TN = 38 K). The low-lying excitons are also investigated at low temperatures and comparisons made with results from earlier Raman, infrared, and neutron scattering work. A detailed analysis of the one-magnon Stokes and anti-Stokes Raman spectra is presented resulting in comprehensive data for the temperature variation up to TN of the one-magnon frequency, line width, and integrated intensity. A theory of the one-magnon scattering and other magnetic transitions is constructed based mainly on a spin S = 3/2 exchange model, extending a simpler effective S = 1/2 approach. The excitation energies and spectral intensities over a broad range of temperatures are obtained using a Green's function equation of motion method that allows for a careful treatment of the single-ion anisotropy. Overall the S = 3/2 theory compares well with the experimental data.

PACS: 75.30.Ds Spin waves;
PACS: 72.10.Вb Scattering by phonons, magnons, and other nonlocalized excitations;
PACS: 78.30.–j Infrared and Raman spectra;
PACS: 75.50.Ee Antiferromagnetics.

Key words: antiferromagnet, inelastic light scattering, magnetic excitations.