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arXiv · 2203.02402

Band-Mott mixing hybridizes the gap in Fe$_2$Mo$_3$O$_8$

K. Park·G. L. Pascut·G. Khanal·M. O. Yokosuk·Xianghan Xu·Bin Gao·M. J. Gutmann·A. P. Litvinchuk·S. -W. Cheong·D. Vanderbilt·K. Haule·J. L. Musfeldt
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Abstract

We combined optical spectroscopy and first principles electronic structure calculations to reveal the charge gap in the polar magnet Fe$_2$Mo$_3$O$_8$. Iron occupation on the octahedral site draws the gap strongly downward compared to the Zn parent compound, and subsequent occupation of the tetrahedral site creates a narrow resonance near the Fermi energy that draws the gap downward even further. This resonance is a many-body effect that emanates from a flat valence band in a Mott-like state due to screening of the local moment - similar to expectations for a Zhang-Rice singlet, except that here, it appears in a semi-conductor. We discuss the unusual hybridization in terms of orbital occupation and character as well as the structure-property relationships that can be unveiled in various metal-substituted systems (Ni, Mn, Co, Zn).

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K. Park, G. L. Pascut, G. Khanal, M. O. Yokosuk, Xianghan Xu, Bin Gao, M. J. Gutmann, A. P. Litvinchuk, S. -W. Cheong, D. Vanderbilt, K. Haule, J. L. Musfeldt. 2022-03-04. Band-Mott mixing hybridizes the gap in Fe$_2$Mo$_3$O$_8$. https://doi.org/10.1103/physrevb.104.195143

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