Hidden Chiral Ferroelectricity in AgNbO$_3$ Perovskite
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866912917653291008 |
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| author | Song, Ying Cao, Lingzhi Zhai, Jinming Yang, Zhilong Yang, Yali Bellaiche, Laurent He, Jiangang |
| author_facet | Song, Ying Cao, Lingzhi Zhai, Jinming Yang, Zhilong Yang, Yali Bellaiche, Laurent He, Jiangang |
| contents | AgNbO$_3$ is a lead-free perovskite with considerable potential for energy storage and optoelectronic applications, yet its low-temperature crystal structure has remained controversial. In this Letter, we revisit its low-energy structural landscape using a systematic first-principles structural search based on symmetry-adapted phonon-mode theory. We uncover a previously unreported chiral ferroelectric phase with space group $R3$, which exhibits a large spontaneous polarization and a low polarization switching barrier, enabling polarization reversal under electric fields. Crucially, the structural chirality of this phase is intrinsically locked to the ferroelectric polarization, allowing electrical control of the chiral handedness. Consequently, chiral optical responses--including circular dichroism, circular photogalvanic effect, optical activity, and second-order nonlinear optics--can be reversibly switched by an external electric field. These results not only clarify the complex low-temperature structural behavior of AgNbO$_3$ but also establish a rare purely inorganic platform for electric-field-tunable chirality, opening a pathway toward ultrafast, electrically controlled chiral optoelectronics. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2602_19036 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Hidden Chiral Ferroelectricity in AgNbO$_3$ Perovskite Song, Ying Cao, Lingzhi Zhai, Jinming Yang, Zhilong Yang, Yali Bellaiche, Laurent He, Jiangang Materials Science AgNbO$_3$ is a lead-free perovskite with considerable potential for energy storage and optoelectronic applications, yet its low-temperature crystal structure has remained controversial. In this Letter, we revisit its low-energy structural landscape using a systematic first-principles structural search based on symmetry-adapted phonon-mode theory. We uncover a previously unreported chiral ferroelectric phase with space group $R3$, which exhibits a large spontaneous polarization and a low polarization switching barrier, enabling polarization reversal under electric fields. Crucially, the structural chirality of this phase is intrinsically locked to the ferroelectric polarization, allowing electrical control of the chiral handedness. Consequently, chiral optical responses--including circular dichroism, circular photogalvanic effect, optical activity, and second-order nonlinear optics--can be reversibly switched by an external electric field. These results not only clarify the complex low-temperature structural behavior of AgNbO$_3$ but also establish a rare purely inorganic platform for electric-field-tunable chirality, opening a pathway toward ultrafast, electrically controlled chiral optoelectronics. |
| title | Hidden Chiral Ferroelectricity in AgNbO$_3$ Perovskite |
| topic | Materials Science |
| url | https://arxiv.org/abs/2602.19036 |