Magnon dressing by orbital excitations in ferromagnetic planes of K2CuF4 and LaMnO3
We show that even when spins and orbitals disentangle in the ground state, spin excitations are renormalized by the local tuning of e _g orbitals in ferromagnetic planes of K _2 CuF _4 and LaMnO _3 . As a result, dressed spin excitations (magnons) obtained within the electronic model propagate as qu...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2019-01-01
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| Series: | New Journal of Physics |
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| Online Access: | https://doi.org/10.1088/1367-2630/aaf0d5 |
| _version_ | 1797750533067374592 |
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| author | Mateusz Snamina Andrzej M Oleś |
| author_facet | Mateusz Snamina Andrzej M Oleś |
| author_sort | Mateusz Snamina |
| collection | DOAJ |
| description | We show that even when spins and orbitals disentangle in the ground state, spin excitations are renormalized by the local tuning of e _g orbitals in ferromagnetic planes of K _2 CuF _4 and LaMnO _3 . As a result, dressed spin excitations (magnons) obtained within the electronic model propagate as quasiparticles and their energy renormalization depends on momentum $\vec{k}$ . Therefore magnons in spin-orbital systems go beyond the paradigm of the effective Heisenberg model with nearest neighbor spin exchange derived from the ground state—spin-orbital entanglement in excited states predicts large magnon softening at the Brillouin zone boundary, and in case of LaMnO _3 the magnon energy at the M = ( π , π ) point may be reduced by ∼45%. In contrast, simultaneously the stiffness constant near the Goldstone mode is almost unaffected. We elucidate physics behind magnon renormalization in spin-orbital systems and explain why long wavelength magnons are unrenormalized while simultaneously energies of short wavelength magnons are reduced by orbital fluctuations. In fact, the $\vec{k}$ -dependence of the magnon energy is modified mainly by dispersion which originates from spin exchange between second neighbors along the cubic axes a and b . |
| first_indexed | 2024-03-12T16:34:07Z |
| format | Article |
| id | doaj.art-0f000a82066f4d6abf8233457e3d0e0e |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-12T16:34:07Z |
| publishDate | 2019-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | New Journal of Physics |
| spelling | doaj.art-0f000a82066f4d6abf8233457e3d0e0e2023-08-08T14:55:52ZengIOP PublishingNew Journal of Physics1367-26302019-01-0121202301810.1088/1367-2630/aaf0d5Magnon dressing by orbital excitations in ferromagnetic planes of K2CuF4 and LaMnO3Mateusz Snamina0Andrzej M Oleś1https://orcid.org/0000-0002-8954-3233Kazimierz Gumiński Department of Theoretical Chemistry, Faculty of Chemistry, Jagiellonian University , Gronostajowa 2, PL-30387 Kraków, PolandMax Planck Institute for Solid State Research , Heisenbergstrasse 1, D-70569 Stuttgart, Germany; Marian Smoluchowski Institute of Physics, Jagiellonian University , Prof. S. Łojasiewicza 11, PL-30348 Kraków, PolandWe show that even when spins and orbitals disentangle in the ground state, spin excitations are renormalized by the local tuning of e _g orbitals in ferromagnetic planes of K _2 CuF _4 and LaMnO _3 . As a result, dressed spin excitations (magnons) obtained within the electronic model propagate as quasiparticles and their energy renormalization depends on momentum $\vec{k}$ . Therefore magnons in spin-orbital systems go beyond the paradigm of the effective Heisenberg model with nearest neighbor spin exchange derived from the ground state—spin-orbital entanglement in excited states predicts large magnon softening at the Brillouin zone boundary, and in case of LaMnO _3 the magnon energy at the M = ( π , π ) point may be reduced by ∼45%. In contrast, simultaneously the stiffness constant near the Goldstone mode is almost unaffected. We elucidate physics behind magnon renormalization in spin-orbital systems and explain why long wavelength magnons are unrenormalized while simultaneously energies of short wavelength magnons are reduced by orbital fluctuations. In fact, the $\vec{k}$ -dependence of the magnon energy is modified mainly by dispersion which originates from spin exchange between second neighbors along the cubic axes a and b .https://doi.org/10.1088/1367-2630/aaf0d5Mott insulatormagnon dressingorbital degeneracyspin-orbital entanglementspin-orbital superexchange |
| spellingShingle | Mateusz Snamina Andrzej M Oleś Magnon dressing by orbital excitations in ferromagnetic planes of K2CuF4 and LaMnO3 New Journal of Physics Mott insulator magnon dressing orbital degeneracy spin-orbital entanglement spin-orbital superexchange |
| title | Magnon dressing by orbital excitations in ferromagnetic planes of K2CuF4 and LaMnO3 |
| title_full | Magnon dressing by orbital excitations in ferromagnetic planes of K2CuF4 and LaMnO3 |
| title_fullStr | Magnon dressing by orbital excitations in ferromagnetic planes of K2CuF4 and LaMnO3 |
| title_full_unstemmed | Magnon dressing by orbital excitations in ferromagnetic planes of K2CuF4 and LaMnO3 |
| title_short | Magnon dressing by orbital excitations in ferromagnetic planes of K2CuF4 and LaMnO3 |
| title_sort | magnon dressing by orbital excitations in ferromagnetic planes of k2cuf4 and lamno3 |
| topic | Mott insulator magnon dressing orbital degeneracy spin-orbital entanglement spin-orbital superexchange |
| url | https://doi.org/10.1088/1367-2630/aaf0d5 |
| work_keys_str_mv | AT mateuszsnamina magnondressingbyorbitalexcitationsinferromagneticplanesofk2cuf4andlamno3 AT andrzejmoles magnondressingbyorbitalexcitationsinferromagneticplanesofk2cuf4andlamno3 |