Importance of the Hubbard U parameter to explore accurate electronic and optical behaviour of BiFeO3

Ghosal, S and Dutta, K and Chowdhury, S and Jana, D (2022) Importance of the Hubbard U parameter to explore accurate electronic and optical behaviour of BiFeO3. In: Journal of Physics D: Applied Physics, 55 (37).

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Abstract

Based upon Hubbard U corrected density functional theory(DFT), the electronic and optical responses of multiferroic Bismuth ferrite(BiFeO3; BFO) have been critically explored. Treating BFO as a strongly correlated insulating system, a Hubbard U parameter is considered for accurate description of localised Fe-3d states. However, the U parameter for the Fe-3d state is not sufficient as 2p states of O atoms are greatly influenced by Fe-3d states. Similar U parameters for Fe-3d as well as O-2p states are considered. An effective U value around 4.3 eV not only solves the band gap mismatch of BFO from both a theoretical and experimental aspect, but also predicts the exact nature of the band gap. Moreover, within this framework, the optical responses of BFO are critically investigated. Multiple transitions appearing in both theoretical and experimental absorption spectra are well explained by crystal field transitions of Fe3+ ions in a d5 high spin state, supported by the density of states curve of BFO. Therefore, based upon the DFT + U approach, accurate electronic and optical characteristics of BFO are critically explored, which is essential for its multidirectional application perspectives.

Item Type:	Journal Article
Publication:	Journal of Physics D: Applied Physics
Publisher:	Institute of Physics
Additional Information:	The copyright for this article belongs to the Institute of Physics.
Keywords:	Bismuth compounds; Density functional theory; Energy gap; Iron compounds; Optical properties, Bismuth ferrites; Density-functional-theory; Electronic behaviors; Hubbard; Hubbard U; Insulating system; Localised; Multiferroics; Optical behaviour; Optical response, Electronic properties
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	10 Aug 2022 05:35
Last Modified:	10 Aug 2022 05:35
URI:	https://eprints.iisc.ac.in/id/eprint/75769

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