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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2310.04615 |
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| _version_ | 1866910380716982272 |
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| author | Zhao, Boyang Ren, Guodong Mei, Hongyan Wu, Vincent C. Singh, Shantanu Jung, Gwan-Yeong Chen, Huandong Giovine, Raynald Niu, Shanyuan Thind, Arashdeep S. Salman, Jad Settineri, Nick S. Chakoumakos, Bryan C. Manley, Michael E. Hermann, Raphael P. Lupini, Andrew R. Chi, Miaofang Hachtel, Jordan A. Simonov, Arkadiy Teat, Simon J. Clément, Raphaële J. Kats, Mikhail A. Ravichandran, J. Mishra, Rohan |
| author_facet | Zhao, Boyang Ren, Guodong Mei, Hongyan Wu, Vincent C. Singh, Shantanu Jung, Gwan-Yeong Chen, Huandong Giovine, Raynald Niu, Shanyuan Thind, Arashdeep S. Salman, Jad Settineri, Nick S. Chakoumakos, Bryan C. Manley, Michael E. Hermann, Raphael P. Lupini, Andrew R. Chi, Miaofang Hachtel, Jordan A. Simonov, Arkadiy Teat, Simon J. Clément, Raphaële J. Kats, Mikhail A. Ravichandran, J. Mishra, Rohan |
| contents | Structural disorder has been shown to enhance and modulate magnetic, electrical, dipolar, electrochemical, and mechanical properties of materials. However, the possibility of obtaining novel optical and optoelectronic properties from structural disorder remains an open question. Here, we show unambiguous evidence of disorder in the form of anisotropic, picoscale atomic displacements modulating the refractive index tensor and resulting in the giant optical anisotropy observed in BaTiS$_3$, a quasi-one-dimensional hexagonal chalcogenide. Single crystal X-ray diffraction studies reveal the presence of antipolar displacements of Ti atoms within adjacent TiS$_6$ chains along the c-axis, and three-fold degenerate Ti displacements in the a-b plane. $^{47/49}$Ti solid-state NMR provides additional evidence for those Ti displacements in the form of a three-horned NMR lineshape resulting from a low symmetry local environment around Ti atoms. We used scanning transmission electron microscopy to directly observe the globally disordered Ti a-b plane displacements and find them to be ordered locally over a few unit cells. First-principles calculations show that the Ti a-b plane displacements selectively reduce the refractive index along the ab-plane, while having minimal impact on the refractive index along the chain direction, thus resulting in a giant enhancement in the optical anisotropy. By showing a strong connection between structural disorder with picoscale displacements and the optical response in BaTiS$_3$, this study opens a pathway for designing optical materials with high refractive index and functionalities such as large optical anisotropy and nonlinearity. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2310_04615 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Giant Modulation of Refractive Index from Picoscale Atomic Displacements Zhao, Boyang Ren, Guodong Mei, Hongyan Wu, Vincent C. Singh, Shantanu Jung, Gwan-Yeong Chen, Huandong Giovine, Raynald Niu, Shanyuan Thind, Arashdeep S. Salman, Jad Settineri, Nick S. Chakoumakos, Bryan C. Manley, Michael E. Hermann, Raphael P. Lupini, Andrew R. Chi, Miaofang Hachtel, Jordan A. Simonov, Arkadiy Teat, Simon J. Clément, Raphaële J. Kats, Mikhail A. Ravichandran, J. Mishra, Rohan Materials Science Mesoscale and Nanoscale Physics Structural disorder has been shown to enhance and modulate magnetic, electrical, dipolar, electrochemical, and mechanical properties of materials. However, the possibility of obtaining novel optical and optoelectronic properties from structural disorder remains an open question. Here, we show unambiguous evidence of disorder in the form of anisotropic, picoscale atomic displacements modulating the refractive index tensor and resulting in the giant optical anisotropy observed in BaTiS$_3$, a quasi-one-dimensional hexagonal chalcogenide. Single crystal X-ray diffraction studies reveal the presence of antipolar displacements of Ti atoms within adjacent TiS$_6$ chains along the c-axis, and three-fold degenerate Ti displacements in the a-b plane. $^{47/49}$Ti solid-state NMR provides additional evidence for those Ti displacements in the form of a three-horned NMR lineshape resulting from a low symmetry local environment around Ti atoms. We used scanning transmission electron microscopy to directly observe the globally disordered Ti a-b plane displacements and find them to be ordered locally over a few unit cells. First-principles calculations show that the Ti a-b plane displacements selectively reduce the refractive index along the ab-plane, while having minimal impact on the refractive index along the chain direction, thus resulting in a giant enhancement in the optical anisotropy. By showing a strong connection between structural disorder with picoscale displacements and the optical response in BaTiS$_3$, this study opens a pathway for designing optical materials with high refractive index and functionalities such as large optical anisotropy and nonlinearity. |
| title | Giant Modulation of Refractive Index from Picoscale Atomic Displacements |
| topic | Materials Science Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2310.04615 |