We use a 30-nm x-ray beam to study the spatially resolved properties of a SmNiO3-based nanodevice that is doped with protons. The x-ray absorption spectra supported by density-functional theory (DFT) simulations show partial reduction of nickel valence in the region with high proton concentration, which leads to the insulating behavior. Concurrently, x-ray diffraction reveals only a small lattice distortion in the doped regions. Together, our results directly show that the knob which proton doping modifies is the electronic valency, and not the crystal lattice. The studies are relevant to on-going efforts to disentangle structural and electronic effects across metal-insulator phase transitions in correlated oxides.
@article{arxiv.2108.06439,
title = {Proton distribution visualization in perovskite nickelate devices utilizing nanofocused X-rays},
author = {Ivan A. Zaluzhnyy and Peter O. Sprau and Richard Tran and Qi Wang and Hai-Tian Zhang and Zhen Zhang and Tae Joon Park and Nelson Hua and Boyan Stoychev and Mathew J. Cherukara and Martin V. Holt and Evgeny Nazarertski and Xiaojing Huang and Hanfei Yan and Ajith Pattammattel and Yong S. Chu and Shyue Ping Ong and Shriram Ramanathan and Oleg G. Shpyrko and Alex Frano},
journal= {arXiv preprint arXiv:2108.06439},
year = {2021}
}