Anomalous lattice anharmonicity and spin-lattice coupling in spin orbit coupled halide K2IrBr6
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| Autores principales: | , , , , , , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866910003847233536 |
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| author | Bhatia, S. Ahmad, A. Zeeshan, M. Kaur, S. Anand, J. K. Goswami, A. Mani, B. K. Sen, K. |
| author_facet | Bhatia, S. Ahmad, A. Zeeshan, M. Kaur, S. Anand, J. K. Goswami, A. Mani, B. K. Sen, K. |
| contents | The interplay between lattice distortions, magnetism, and spin-orbit coupling in 5d transition-metal halides offers a fertile platform for exploring correlated spin-lattice dynamics. Here, we investigate the impact of structural symmetry breaking on lattice vibrations and local spin environments in the antifluorite compound K2IrBr6 using temperature dependent Raman spectroscopy, electron paramagnetic resonance (EPR), and first-principles lattice dynamics calculations. K2IrBr6 undergoes successive cubic-to-tetragonal and tetragonal-to-monoclinic phase transitions at 170 K and 122 K, respectively, driven by cooperative distortions of the IrBr6 octahedra. Raman spectroscopy reveals anomalous phonon linewidth broadening and unconventional temperature dependence of phonon energies near these transitions, indicating that dynamic spin-phonon coupling is significant well above the Neel temperature (16 K). First-principles phonon calculations support the mode assignments and demonstrate that symmetry-lowering distortions significantly renormalize vibrational modes, consistent with the experimental observations. Complementary EPR measurements detect anisotropic g-factors, resonance field shifts, and linewidth narrowing across the structural transitions, reflecting the emergence of static spin-lattice correlations mediated by spin-orbit entanglement. These findings establish K2IrBr6 as a model system where halide ligand fields, octahedral distortions, and SOC collaboratively govern spin-lattice coupling, providing chemical pathways to engineer quantum materials with tunable magnetic and lattice responses. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_08204 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Anomalous lattice anharmonicity and spin-lattice coupling in spin orbit coupled halide K2IrBr6 Bhatia, S. Ahmad, A. Zeeshan, M. Kaur, S. Anand, J. K. Goswami, A. Mani, B. K. Sen, K. Strongly Correlated Electrons The interplay between lattice distortions, magnetism, and spin-orbit coupling in 5d transition-metal halides offers a fertile platform for exploring correlated spin-lattice dynamics. Here, we investigate the impact of structural symmetry breaking on lattice vibrations and local spin environments in the antifluorite compound K2IrBr6 using temperature dependent Raman spectroscopy, electron paramagnetic resonance (EPR), and first-principles lattice dynamics calculations. K2IrBr6 undergoes successive cubic-to-tetragonal and tetragonal-to-monoclinic phase transitions at 170 K and 122 K, respectively, driven by cooperative distortions of the IrBr6 octahedra. Raman spectroscopy reveals anomalous phonon linewidth broadening and unconventional temperature dependence of phonon energies near these transitions, indicating that dynamic spin-phonon coupling is significant well above the Neel temperature (16 K). First-principles phonon calculations support the mode assignments and demonstrate that symmetry-lowering distortions significantly renormalize vibrational modes, consistent with the experimental observations. Complementary EPR measurements detect anisotropic g-factors, resonance field shifts, and linewidth narrowing across the structural transitions, reflecting the emergence of static spin-lattice correlations mediated by spin-orbit entanglement. These findings establish K2IrBr6 as a model system where halide ligand fields, octahedral distortions, and SOC collaboratively govern spin-lattice coupling, providing chemical pathways to engineer quantum materials with tunable magnetic and lattice responses. |
| title | Anomalous lattice anharmonicity and spin-lattice coupling in spin orbit coupled halide K2IrBr6 |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2503.08204 |