Photoinduced orbital polarization and Jahn-Teller effect in RNiO$_3$
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| Main Authors: | , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866911610722844672 |
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| author | Rajpurohit, Sangeeta Haque, Sheikh Rubaiat Ul Lindenberg, Aaron M. Blöchl, Peter E. Ogitsu, Tadashi |
| author_facet | Rajpurohit, Sangeeta Haque, Sheikh Rubaiat Ul Lindenberg, Aaron M. Blöchl, Peter E. Ogitsu, Tadashi |
| contents | The orbital degree of freedom in rare-earth nickelates is typically inactive across the temperature-driven metal-insulator transition, where the system develops two inequivalent Ni sites associated with Ni-O bond disproportionation and breathing-mode distortions of NiO$_6$ octahedra. Here, we show that orbital polarization can be induced by optical excitation with linearly polarized light. Using an interacting multiband tight-binding model combined with real-time simulations of coupled electron-ion-spin dynamics, we find that photoinduced $d$-$d$ transitions reduce the local magnetic moments at Ni sites and effectively suppress Hund's coupling $J$ in the excited state. Importantly, these transitions can be made strongly orbital-selective by tuning the light polarization, leading to an imbalance in $e_g$ orbital occupancies. The resulting nonequilibrium state, characterized by reduced effective $J$ and unequal orbital populations, becomes unstable toward Jahn-Teller (JT) distortions, driving structural relaxation along coherently excited JT modes. Our results demonstrate that polarization-controlled optical excitation provides a pathway to access hidden nonthermal phases with emergent orbital order, enabling coherent control of coupled charge, spin, and lattice degrees of freedom on ultrafast timescales. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_18524 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Photoinduced orbital polarization and Jahn-Teller effect in RNiO$_3$ Rajpurohit, Sangeeta Haque, Sheikh Rubaiat Ul Lindenberg, Aaron M. Blöchl, Peter E. Ogitsu, Tadashi Strongly Correlated Electrons The orbital degree of freedom in rare-earth nickelates is typically inactive across the temperature-driven metal-insulator transition, where the system develops two inequivalent Ni sites associated with Ni-O bond disproportionation and breathing-mode distortions of NiO$_6$ octahedra. Here, we show that orbital polarization can be induced by optical excitation with linearly polarized light. Using an interacting multiband tight-binding model combined with real-time simulations of coupled electron-ion-spin dynamics, we find that photoinduced $d$-$d$ transitions reduce the local magnetic moments at Ni sites and effectively suppress Hund's coupling $J$ in the excited state. Importantly, these transitions can be made strongly orbital-selective by tuning the light polarization, leading to an imbalance in $e_g$ orbital occupancies. The resulting nonequilibrium state, characterized by reduced effective $J$ and unequal orbital populations, becomes unstable toward Jahn-Teller (JT) distortions, driving structural relaxation along coherently excited JT modes. Our results demonstrate that polarization-controlled optical excitation provides a pathway to access hidden nonthermal phases with emergent orbital order, enabling coherent control of coupled charge, spin, and lattice degrees of freedom on ultrafast timescales. |
| title | Photoinduced orbital polarization and Jahn-Teller effect in RNiO$_3$ |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2604.18524 |