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Oxygen vacancy induced electronic structure modification of KTaO3

Ojha, SK and Gogoi, SK and Mandal, P and Kaushik, SD and Freeland, JW and Jain, M and Middey, S (2021) Oxygen vacancy induced electronic structure modification of KTaO3. In: Physical Review B, 103 (8).

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Official URL: https://doi.org/10.1103/PhysRevB.103.085120


The observation of a metallic interface between band insulators LaAlO3 and SrTiO3 has led to massive efforts to understand the origin of the phenomenon as well as to search for other systems hosting such two-dimensional electron gases (2-DEGs). However, the understanding of the origin of the 2-DEG is very often hindered as several possible mechanisms such as polar catastrophe, cationic intermixing, and oxygen vacancy (OV) can be operative simultaneously. The presence of a heavy element makes the KTaO3 (KTO) based 2-DEG a potential platform to investigate spin-orbit coupling driven novel electronic and magnetic phenomena. In this work, we investigate the sole effect of OV in KTO, which makes KTO metallic. O K-edge x-ray absorption spectroscopy measurements find that OV dopes electrons in Ta t2g∗ antibonding states. Photoluminescence measurements reveal the existence of a highly localized deep midgap state in oxygen-deficient KTO. Our detailed ab initio calculations demonstrate that such deep midgap state arises due to the linear clustering of OVs around Ta. Our present work emphasizes that we must pay attention to the possible presence of OVs in interpreting emergent behavior of KTO-based heterostructures.

Item Type: Journal Article
Publication: Physical Review B
Publisher: American Physical Society
Additional Information: The copyright for this article belongs to the Author.
Keywords: Aluminum compounds; Calculations; Electronic structure; Lanthanum compounds; Oxygen; Spin orbit coupling; Strontium titanates; Tantalum metallography; Titanium compounds; Two dimensional electron gas; X ray absorption spectroscopy, Ab initio calculations; Anti-bonding state; Emergent behaviors; Magnetic phenomena; Metallic interfaces; Photoluminescence measurements; Possible mechanisms; Structure modification, Oxygen vacancies
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 28 Jul 2023 09:09
Last Modified: 28 Jul 2023 09:09
URI: https://eprints.iisc.ac.in/id/eprint/82674

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