Above Room Temperature Ferroelectricity in Epitaxially Strained KTaO3
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arXiv
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| Main Authors: | , , , , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866909997513834496 |
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| author | Schwaigert, Tobias Salmani-Rezaie, Salva Hazra, Sankalpa Saha, Utkarsh Ramesh, Maya Ross, Aiden Pamuk, Betul Chen, Long-Qing Muller, David A. Schlom, Darrell G. Gopalan, Venkatraman Ahadi, Kaveh |
| author_facet | Schwaigert, Tobias Salmani-Rezaie, Salva Hazra, Sankalpa Saha, Utkarsh Ramesh, Maya Ross, Aiden Pamuk, Betul Chen, Long-Qing Muller, David A. Schlom, Darrell G. Gopalan, Venkatraman Ahadi, Kaveh |
| contents | Epitaxial strain is a powerful means to engineer emergent phenomena in thin films and heterostructures. Here, we demonstrate that KTaO3, a cubic perovskite in bulk form, can be epitaxially strained into a highly tunable ferroelectric. KTaO3 films grown commensurate to SrTiO3 (001) substrates experience an in-plane strain of -2.1 % that transforms the cubic structure into a tetragonal polar phase with transition temperature of 475 K, consistent with our thermodynamic calculations. We show that the Curie temperature and the spontaneous electric polarization can be system- atically controlled with epitaxial strain. Scanning transmission electron microscopy reveals cooperative polar displacements of the potassium columns with respect to the neighboring tantalum columns at room temperature. Optical second-harmonic generation results are described by a tetragonal polar point group (4mm), indicating the emergence of a global polar ground state. We observe a ferroelectric hysteresis response, using metal-insulator-metal capacitor test structures. The results demon- strate a robust intrinsic ferroelectric state in epitaxially strained KTaO3 thin films. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2601_14627 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Above Room Temperature Ferroelectricity in Epitaxially Strained KTaO3 Schwaigert, Tobias Salmani-Rezaie, Salva Hazra, Sankalpa Saha, Utkarsh Ramesh, Maya Ross, Aiden Pamuk, Betul Chen, Long-Qing Muller, David A. Schlom, Darrell G. Gopalan, Venkatraman Ahadi, Kaveh Materials Science Epitaxial strain is a powerful means to engineer emergent phenomena in thin films and heterostructures. Here, we demonstrate that KTaO3, a cubic perovskite in bulk form, can be epitaxially strained into a highly tunable ferroelectric. KTaO3 films grown commensurate to SrTiO3 (001) substrates experience an in-plane strain of -2.1 % that transforms the cubic structure into a tetragonal polar phase with transition temperature of 475 K, consistent with our thermodynamic calculations. We show that the Curie temperature and the spontaneous electric polarization can be system- atically controlled with epitaxial strain. Scanning transmission electron microscopy reveals cooperative polar displacements of the potassium columns with respect to the neighboring tantalum columns at room temperature. Optical second-harmonic generation results are described by a tetragonal polar point group (4mm), indicating the emergence of a global polar ground state. We observe a ferroelectric hysteresis response, using metal-insulator-metal capacitor test structures. The results demon- strate a robust intrinsic ferroelectric state in epitaxially strained KTaO3 thin films. |
| title | Above Room Temperature Ferroelectricity in Epitaxially Strained KTaO3 |
| topic | Materials Science |
| url | https://arxiv.org/abs/2601.14627 |