1. Effect of random antiferromagnetic exchange on the spin waves in a three-dimensional Heisenberg ferromagnet
- Author
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Hameed, S., Wang, Z., Gautreau, D. M., Joe, J., Olson, K. P., Chi, S., Gehring, P. M., Hong, T., Pajerowski, D. M., Williams, T. J., Xu, Z., Matsuda, M., Birol, T., Fernandes, R. M., and Greven, M.
- Subjects
Condensed Matter - Strongly Correlated Electrons - Abstract
Neutron scattering is used to study spin waves in the three-dimensional Heisenberg ferromagnet YTiO$_3$, with spin-spin exchange disorder introduced $via$ La-substitution at the Y site. No significant changes are observed in the spin-wave dispersion up to a La concentration of 20%. However, a strong broadening of the spectrum is found, indicative of shortened spin-wave lifetimes. Density-functional theory calculations predict minimal changes in exchange constants as a result of average structural changes due to La substitution, in agreement with the data. The absence of significant changes in the spin-wave dispersion, the considerable lifetime effect, and the reduced ordered magnetic moment previously observed in the La-substituted system are qualitatively captured by an isotropic, nearest-neighbor, three-dimensional Heisenberg ferromagnet model with random antiferromagnetic exchange. We therefore establish Y$_{1-x}$La$_x$TiO$_3$ as a model system to study the effect of antiferromagnetic spin-exchange disorder in a three-dimensional Heisenberg ferromagnet., Comment: 6 pages and 5 figures in main text. Supplementary material included
- Published
- 2023
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