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arXiv · 1811.11117

Hole-Induced Electronic and Optical Transitions in La1-xSrxFeO3 Epitaxial Thin Films

Le Wang·Yingge Du·Peter V. Sushko·Mark E. Bowden·Kelsey A. Stoerzinger·Steven M. Heald·Mark. D. Scafetta·Tiffany C. Kaspar·Scott. A Chambers
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Abstract

We have investigated the electronic and optical properties of epitaxial La1-xSrxFeO3 for x from 0 to 1 prepared by molecular beam epitaxy. Core-level and valence-band x-ray photoemission features monotonically shift to lower binding energy with increasing x, indicating downward movement of the Fermi level toward to the valence band maximum. Both Fe 2p and O 1s spectra broaden to higher binding energy with increasing x, consistent with delocalization of Sr-induced holes in the Fe 3d/O 2p hybridized valence band. Combining X-ray valence band photoemission and O K-edge x-ray absorption data, we map the evolution of the occupied and unoccupied bands and observe a narrowing of the gap, along with a transfer of state density from just below to just above the Fermi level, resulting from hole doping. In-plane transport measurements confirm that the material becomes a p-type semiconductor at lower doping levels and exhibits a insulator-to-metal transition at x equal to 1. Sub-gap optical transitions revealed by spectroscopic ellipsometry are explained based on insight from theoretical densities of states and first-principles calculations of optical absorption spectra.

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Le Wang, Yingge Du, Peter V. Sushko, Mark E. Bowden, Kelsey A. Stoerzinger, Steven M. Heald, Mark. D. Scafetta, Tiffany C. Kaspar, Scott. A Chambers. 2018-11-27. Hole-Induced Electronic and Optical Transitions in La1-xSrxFeO3 Epitaxial Thin Films. https://doi.org/10.1103/physrevmaterials.3.025401

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