TY  - JOUR
AU  - Rogge, Paul C.
AU  - Chandrasena, Ravini U.
AU  - Cammarata, Antonio
AU  - Green, Robert J.
AU  - Shafer, Padraic
AU  - Lefler, Benjamin M.
AU  - Huon, Amanda
AU  - Arab, Arian
AU  - Arenholz, Elke
AU  - Lee, Ho Nyung
AU  - Lee, Tien-Lin
AU  - Nemsak, Slavomir
AU  - Rondinelli, James M.
AU  - Gray, Alexander X.
AU  - May, Steven J.
TI  - Electronic structure of negative charge transfer CaFeO 3 across the metal-insulator transition
JO  - Physical review materials
VL  - 2
IS  - 1
SN  - 2475-9953
CY  - College Park, MD
PB  - APS
M1  - FZJ-2019-00554
SP  - 015002
PY  - 2018
AB  - We investigated the metal-insulator transition for epitaxial thin films of the perovskite CaFeO3, a material with a significant oxygen ligand hole contribution to its electronic structure. We find that biaxial tensile and compressive strain suppress the metal-insulator transition temperature. By combining hard x-ray photoelectron spectroscopy, soft x-ray absorption spectroscopy, and density functional calculations, we resolve the element-specific changes to the electronic structure across the metal-insulator transition. We demonstrate that the Fe sites undergo no observable spectroscopic change between the metallic and insulating states, whereas the O electronic configuration undergoes significant changes. This strongly supports the bond-disproportionation model of the metal-insulator transition for CaFeO3 and highlights the importance of ligand holes in its electronic structure. By sensitively measuring the ligand hole density, however, we find that it increases by ∼5–10% in the insulating state, which we ascribe to a further localization of electron charge on the Fe sites. These results provide detailed insight into the metal-insulator transition of negative charge transfer compounds and should prove instructive for understanding metal-insulator transitions in other late transition metal compounds such as the nickelates.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000423527600003
DO  - DOI:10.1103/PhysRevMaterials.2.015002
UR  - https://juser.fz-juelich.de/record/859717
ER  -