Origin and dynamics of umbrella states in rare-earth iron garnets
| Autor: | Tomasello, Bruno, Mannix, Dan, Geprägs, Stephan, Ziman, Timothy |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Annals of Physics, page 169117, Elsevier, available online 24 September 2022 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1016/j.aop.2022.169117 |
| Popis: | Rare-earth iron garnets $R_{3}$Fe$_{5}$O$_{12}$ are fascinating insulators with very diverse magnetic phases. Their strong potential in spintronic devices has encouraged a renewal of interest in the study of their low temperature spin structures and spin wave dynamics. A striking feature of rare-earth garnets with $R$-ions exhibiting strong crystal-field effects like Tb-, Dy-, Ho-, and Er-ions is the observation of low-temperature non-collinear magnetic structures featuring "umbrella-like" arrangements of the rare-earth magnetic moments. In this study, we demonstrate that such umbrella magnetic states are naturally emerging from the crystal-field anisotropies of the rare-earth ions. By means of a general model endowed with only the necessary elements from the crystal structure, we show how umbrella-like spin structures can take place and calculate the canting-angle as a result of the competition between the exchange-interaction of the rare-earth and the iron ions as well as the crystal-field anisotropy. Our results are compared to experimental data, and a study of the polarised spin wave dynamics is presented. Our study improves the understanding of umbrella-like spin structures and paves the way for more complex spin wave calculations in rare-earth iron garnets with non-collinear magnetic phases. Comment: 8 pages, 7 figures |
| Databáze: | arXiv |
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