Magnetic and thermodynamic properties of Sr_{2}LaFe_{3}O_{9}
arXiv:cond-mat/9703044 · doi:10.1016/S0304-8853(97)00084-X
Abstract
Using a Dirac-Heisenberg Hamiltonian with biquadratic exchange interactions, we study the effect of iron disproportionation on the magnetic ordering, and describe the first-order magnetic transition occurring in the perovskite Sr_{2}LaFe_{3}O_{9}. Upon fitting the experimental data, we give an estimate of the exchange integrals for the antiferromagntic and ferromagnetic interactions, in agreement with previous works on kindered compounds. Spin-wave theory yields a magnon spectrum with a gapless antiferromagnetic mode together with two gapped ferromagnetic ones.
8 pages of RevTex, 5 figures (available upon request), submitted to J. Mag. Mag. Mat