Abstract
Neutron scattering is used to study spin waves in the three-dimensional Heisenberg ferromagnet YTiO3, 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 Y1-xLaxTiO3 as a model system for the study of antiferromagnetic spin-exchange disorder in a three-dimensional Heisenberg ferromagnet.
| Original language | English |
|---|---|
| Article number | 134406 |
| Journal | Physical Review B |
| Volume | 108 |
| Issue number | 13 |
| DOIs | |
| State | Published - Oct 1 2023 |
Funding
The work at University of Minnesota was funded by the Department of Energy through the University of Minnesota Center for Quantum Materials, under Grant No. DE-SC0016371. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from the NSF through the MRSEC (Award No. DMR-2011401) and the NNCI (Award No. ECCS-2025124) programs. A portion of this research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. We acknowledge the support of the National Institute of Standards and Technology, U.S. Department of Commerce, in providing the neutron research facilities used in this work.