Electron quasi-itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetism
We point out the emergence of magnetism from the interplay of electron quasi-itinerancy and quantum order by disorder in pyrochlore iridates. Like other Mott insulating iridates, the Ir^{4+} ion in pyrochlore iridates develops an effective J=1/2 moment from the on-site spin-orbit coupling. We consid...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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American Physical Society
2020-11-01
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| Series: | Physical Review Research |
| Online Access: | http://doi.org/10.1103/PhysRevResearch.2.043273 |
| _version_ | 1797211228131557376 |
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| author | Gang Chen Xiaoqun Wang |
| author_facet | Gang Chen Xiaoqun Wang |
| author_sort | Gang Chen |
| collection | DOAJ |
| description | We point out the emergence of magnetism from the interplay of electron quasi-itinerancy and quantum order by disorder in pyrochlore iridates. Like other Mott insulating iridates, the Ir^{4+} ion in pyrochlore iridates develops an effective J=1/2 moment from the on-site spin-orbit coupling. We consider the generic symmetry-allowed exchange between these local moments on a pyrochlore lattice and obtain the mean-field phase diagram. Assuming the superexchange is mediated by direct and/or indirect electron hopping via intermediate oxygens, we derive the exchange interactions in the strong-coupling regime from the Hubbard model. This exchange has a degenerate classical ground-state manifold, and quantum fluctuation selects a noncoplanar ground state, known as quantum order by disorder. Extending to the intermediate-coupling regime, the same noncoplanar order is selected from the degenerate manifold by the kinetic energy, which is dubbed “electron quasi-itinerancy.” We discuss the experimental relevance of our results and electron quasi-itinerancy among other iridates and 4d/5d magnets. |
| first_indexed | 2024-04-24T10:23:09Z |
| format | Article |
| id | doaj.art-bf60867e49cc4fab8fed9f4937c83e73 |
| institution | Directory Open Access Journal |
| issn | 2643-1564 |
| language | English |
| last_indexed | 2024-04-24T10:23:09Z |
| publishDate | 2020-11-01 |
| publisher | American Physical Society |
| record_format | Article |
| series | Physical Review Research |
| spelling | doaj.art-bf60867e49cc4fab8fed9f4937c83e732024-04-12T17:04:18ZengAmerican Physical SocietyPhysical Review Research2643-15642020-11-012404327310.1103/PhysRevResearch.2.043273Electron quasi-itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetismGang ChenXiaoqun WangWe point out the emergence of magnetism from the interplay of electron quasi-itinerancy and quantum order by disorder in pyrochlore iridates. Like other Mott insulating iridates, the Ir^{4+} ion in pyrochlore iridates develops an effective J=1/2 moment from the on-site spin-orbit coupling. We consider the generic symmetry-allowed exchange between these local moments on a pyrochlore lattice and obtain the mean-field phase diagram. Assuming the superexchange is mediated by direct and/or indirect electron hopping via intermediate oxygens, we derive the exchange interactions in the strong-coupling regime from the Hubbard model. This exchange has a degenerate classical ground-state manifold, and quantum fluctuation selects a noncoplanar ground state, known as quantum order by disorder. Extending to the intermediate-coupling regime, the same noncoplanar order is selected from the degenerate manifold by the kinetic energy, which is dubbed “electron quasi-itinerancy.” We discuss the experimental relevance of our results and electron quasi-itinerancy among other iridates and 4d/5d magnets.http://doi.org/10.1103/PhysRevResearch.2.043273 |
| spellingShingle | Gang Chen Xiaoqun Wang Electron quasi-itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetism Physical Review Research |
| title | Electron quasi-itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetism |
| title_full | Electron quasi-itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetism |
| title_fullStr | Electron quasi-itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetism |
| title_full_unstemmed | Electron quasi-itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetism |
| title_short | Electron quasi-itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetism |
| title_sort | electron quasi itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetism |
| url | http://doi.org/10.1103/PhysRevResearch.2.043273 |
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