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| Main Authors: | , , , , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2604.21783 |
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| _version_ | 1866918464583630848 |
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| author | Jindata, Warakorn Vo, Trung-Phuc Jaisuk, Chutchawan Mo, Sung-Kwan Nguyen, Thanh-Tien Minár, Ján Meevasana, Worawat |
| author_facet | Jindata, Warakorn Vo, Trung-Phuc Jaisuk, Chutchawan Mo, Sung-Kwan Nguyen, Thanh-Tien Minár, Ján Meevasana, Worawat |
| contents | In this work, we investigate and compare the electronic structures of SrTiO3 and KTaO3 under ultraviolet (UV) light induced electron doping. Using angle-resolved photoemission spectroscopy (ARPES), the evolution of the surface electronic structures of SrTiO3 and KTaO3 is systematically examined as a function of electron density. In contrast to KTaO3, SrTiO3 exhibits a pronounced shrinking of its surface bandgap by approximately 390 meV, accompanied by a counterintuitive shift of the valence band peak toward lower binding energies of up to 200 meV with increasing electron density. This anomalous behavior constitutes a spectroscopic signature of negative electronic compressibility (NEC). Density-functional-theory calculations provide qualitative support for the experimental observations. The calculations show that surface formation already reduces the apparent near-gap separation in SrTiO3, while additional electron accumulation further drives the slab toward a more metallic state; oxygen-vacancy models likewise produce strong bandgap reduction, identifying plausible mechanisms contributing to the observed surface bandgap shrinkage. These findings establish a direct spectroscopic link between bandgap engineering and the NEC effect at the SrTiO3 surface, highlighting the potential of SrTiO3 for next-generation oxide electronic, optoelectronic, and high-performance capacitive energy storage devices applications. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_21783 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Direct observation of surface bandgap shrinkage and negative electronic compressibility in SrTiO3 Jindata, Warakorn Vo, Trung-Phuc Jaisuk, Chutchawan Mo, Sung-Kwan Nguyen, Thanh-Tien Minár, Ján Meevasana, Worawat Materials Science In this work, we investigate and compare the electronic structures of SrTiO3 and KTaO3 under ultraviolet (UV) light induced electron doping. Using angle-resolved photoemission spectroscopy (ARPES), the evolution of the surface electronic structures of SrTiO3 and KTaO3 is systematically examined as a function of electron density. In contrast to KTaO3, SrTiO3 exhibits a pronounced shrinking of its surface bandgap by approximately 390 meV, accompanied by a counterintuitive shift of the valence band peak toward lower binding energies of up to 200 meV with increasing electron density. This anomalous behavior constitutes a spectroscopic signature of negative electronic compressibility (NEC). Density-functional-theory calculations provide qualitative support for the experimental observations. The calculations show that surface formation already reduces the apparent near-gap separation in SrTiO3, while additional electron accumulation further drives the slab toward a more metallic state; oxygen-vacancy models likewise produce strong bandgap reduction, identifying plausible mechanisms contributing to the observed surface bandgap shrinkage. These findings establish a direct spectroscopic link between bandgap engineering and the NEC effect at the SrTiO3 surface, highlighting the potential of SrTiO3 for next-generation oxide electronic, optoelectronic, and high-performance capacitive energy storage devices applications. |
| title | Direct observation of surface bandgap shrinkage and negative electronic compressibility in SrTiO3 |
| topic | Materials Science |
| url | https://arxiv.org/abs/2604.21783 |