Cluster rearrangement by chiral charge order in lacunar spinel GaNb$_4$Se$_8$
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arXiv
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| Autori principali: | , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| _version_ | 1866911793278877696 |
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| author | Kitou, Shunsuke Gen, Masaki Nakamura, Yuiga Tokunaga, Yusuke Arima, Taka-hisa |
| author_facet | Kitou, Shunsuke Gen, Masaki Nakamura, Yuiga Tokunaga, Yusuke Arima, Taka-hisa |
| contents | Transition-metal atoms with d electrons sometimes form clusters in crystals, which significantly affects the physical properties. Such a cluster formation frequently accompanies a change in the crystal system, leading to the presence of domains with different crystal orientations. In particular, the cubic symmetry is rarely retained after the cluster formation. Here, we identify a cubic-to-cubic phase transition in lacunar spinel GaNb$_4$Se$_8$, where the change in the lattice parameter is less than 0.0001%. Each Nb$^{3.25+}$ tetramer with seven 4d electrons is distorted into a Nb$^{3+}$ trimer and a Nb$^{4+}$ monomer induced by charge disproportionation among Nb ions. While the Nb$^{3+}$ trimer with six 4d electrons forms spin-singlets in the sigma-bonding orbitals for three Nb-Nb bonds, a localized S=1/2 spin remains on the Nb$^{4+}$ ion. Furthermore, a local electric dipole moment is induced along the three-fold rotation axis of each distorted tetramer by the cluster rearrangement. The electric dipole moments are regularly arranged to maintain the cubic symmetry, giving rise to chiral order. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_03803 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Cluster rearrangement by chiral charge order in lacunar spinel GaNb$_4$Se$_8$ Kitou, Shunsuke Gen, Masaki Nakamura, Yuiga Tokunaga, Yusuke Arima, Taka-hisa Strongly Correlated Electrons Transition-metal atoms with d electrons sometimes form clusters in crystals, which significantly affects the physical properties. Such a cluster formation frequently accompanies a change in the crystal system, leading to the presence of domains with different crystal orientations. In particular, the cubic symmetry is rarely retained after the cluster formation. Here, we identify a cubic-to-cubic phase transition in lacunar spinel GaNb$_4$Se$_8$, where the change in the lattice parameter is less than 0.0001%. Each Nb$^{3.25+}$ tetramer with seven 4d electrons is distorted into a Nb$^{3+}$ trimer and a Nb$^{4+}$ monomer induced by charge disproportionation among Nb ions. While the Nb$^{3+}$ trimer with six 4d electrons forms spin-singlets in the sigma-bonding orbitals for three Nb-Nb bonds, a localized S=1/2 spin remains on the Nb$^{4+}$ ion. Furthermore, a local electric dipole moment is induced along the three-fold rotation axis of each distorted tetramer by the cluster rearrangement. The electric dipole moments are regularly arranged to maintain the cubic symmetry, giving rise to chiral order. |
| title | Cluster rearrangement by chiral charge order in lacunar spinel GaNb$_4$Se$_8$ |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2401.03803 |