Dielectric softening in the halide double perovskites $A_2$Au$_2X_6$ ($A$: Cs, Rb; $X$: Cl, Br, I) via a strain-mediated pseudotriggered mechanism
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arXiv
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| Format: | Preprint |
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2025
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| author | Dey, Urmimala Cowell, Jordan A. R. Bristowe, Nicholas C. |
| author_facet | Dey, Urmimala Cowell, Jordan A. R. Bristowe, Nicholas C. |
| contents | Halide perovskites have emerged as promising candidates for next generation photovoltaic applications, attracting significant attention in recent years. Through first-principles calculations combined with group-theoretical analyses, we investigate the structural phase diagram of Pb-free Jahn-Teller-active $A_2$Au$_2X_6$ ($A$: Cs, Rb; $X$: Cl, Br, I) double perovskites. Our study identifies a previously unreported ferroelectric phase, where the softening of the polar mode$, $key to ferroelectricity, is driven by an unconventional and indirect coupling with improper strains originating from Jahn-Teller distortions. The proposed strain mediated \textit{pseudo}triggered mechanism offers an alternative pathway to enhance the static dielectric constant or even promote (photo-)ferroelectricity, addressing challenges such as defects, excitons, and charge scattering that hinder photovoltaic efficiency. More broadly, this unique mechanism could be extended to oxide double perovskites and opens up a new type of ferroelectric phase transition worthy of future investigation. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_09259 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Dielectric softening in the halide double perovskites $A_2$Au$_2X_6$ ($A$: Cs, Rb; $X$: Cl, Br, I) via a strain-mediated pseudotriggered mechanism Dey, Urmimala Cowell, Jordan A. R. Bristowe, Nicholas C. Materials Science Halide perovskites have emerged as promising candidates for next generation photovoltaic applications, attracting significant attention in recent years. Through first-principles calculations combined with group-theoretical analyses, we investigate the structural phase diagram of Pb-free Jahn-Teller-active $A_2$Au$_2X_6$ ($A$: Cs, Rb; $X$: Cl, Br, I) double perovskites. Our study identifies a previously unreported ferroelectric phase, where the softening of the polar mode$, $key to ferroelectricity, is driven by an unconventional and indirect coupling with improper strains originating from Jahn-Teller distortions. The proposed strain mediated \textit{pseudo}triggered mechanism offers an alternative pathway to enhance the static dielectric constant or even promote (photo-)ferroelectricity, addressing challenges such as defects, excitons, and charge scattering that hinder photovoltaic efficiency. More broadly, this unique mechanism could be extended to oxide double perovskites and opens up a new type of ferroelectric phase transition worthy of future investigation. |
| title | Dielectric softening in the halide double perovskites $A_2$Au$_2X_6$ ($A$: Cs, Rb; $X$: Cl, Br, I) via a strain-mediated pseudotriggered mechanism |
| topic | Materials Science |
| url | https://arxiv.org/abs/2503.09259 |