Raman Scattering by Magnetic Excitations in RbNiF3

• Published in: Journal of applied physics 1969-03, Vol.40 (3), p.1603-1604
• Main Authors: Chinn, S. R., Zeiger, H. J., O'Connor, J. R.
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.1657794

An investigation of Raman scattering of argon laser light (λ=5145 Å) from the hexagonal ferrimagnet RbNiF3 revealed at T≅15°K an intense, broad, symmetrical line shifted ∼510 cm−1 from the laser excitation energy. At higher temperatures as its amplitude decreased, the line broadened and its shift decreased. It was still intense at the Curie temperature (139°K), and remained observable to temperatures near 200°K. This line, assumed to arise from magnetic excitations, is best described in the ordered state as due to two magnon scattering, and at Tc and above due to scattering from a cluster. From the computed magnon modes and energies, optical absorption data, and susceptibility measurements, we determine a set of exchange constants for RbNiF3. These constants are then used to relate computed magnetic properties with the results of NMR and other measurements. Comparison of the Raman shifts with the predictions of a molecular field model are used to obtain estimates of the short-range order persisting above Tc.