Report
Bond Ordering and Molecular Spin-Orbital Fluctuations in the Cluster Mott Insulator GaTa$_4$Se$_8$
| العنوان: | Bond Ordering and Molecular Spin-Orbital Fluctuations in the Cluster Mott Insulator GaTa$_4$Se$_8$ |
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| المؤلفون: | Yang, Tsung-Han, Kawamoto, S., Higo, Tomoya, Wang, SuYin Grass, Stone, M. B., Neuefeind, Joerg, Ruff, Jacob P. C., Abeykoon, A. M. Milinda, Chen, Yu-Sheng, Nakatsuji, S., Plumb, K. W. |
| المصدر: | Phys. Rev. Research 4, 033123 (2022) |
| سنة النشر: | 2022 |
| المجموعة: | Condensed Matter |
| مصطلحات موضوعية: | Condensed Matter - Strongly Correlated Electrons |
| الوصف: | For materials where spin-orbit coupling is competitive with electronic correlations, the spatially anisotropic spin-orbital wavefunctions can stabilize degenerate states that lead to many and diverse quantum phases of matter. Here, we find evidence for a dynamical spin-orbital state preceding a T$^*$=50 K order-disorder spin-orbital ordering transition in the $j\!=\!3/2$ lacunar spinel GaTa$_4$Se$_8$. Above T$^*$, GaTa$_4$Se$_8$ has an average cubic crystal structure, but total scattering measurements indicate local non-cubic distortions of Ta$_4$ tetrahedral clusters for all measured temperatures $2 < T < 300$ K. Inelastic neutron scattering measurements reveal the dynamic nature of these local distortions through symmetry forbidden optical phonon modes that modulate $j\!=\!3/2$ molecular orbital occupation as well as intercluster Ta-Se bonds. Spin-orbital ordering at T$^*$ cannot be attributed to a classic Jahn-Teller mechanism and based on our findings, we propose that intercluster interactions acting on the scale of T$^*$ act to break global symmetry. The resulting staggered intercluster dimerization pattern doubles the unit cell, reflecting a spin-orbital valence bond ground state. Comment: 13 pages, 8 figures |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1103/PhysRevResearch.4.033123 |
| URL الوصول: | http://arxiv.org/abs/2206.07738 |
| رقم الانضمام: | edsarx.2206.07738 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1103/PhysRevResearch.4.033123 |
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