Proton distribution visualization in perovskite nickelate devices utilizing nanofocused x rays

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 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 ongoing efforts to disentangle structural and electronic effects across metal-insulator phase transitions in correlated oxides.

Automated summary

The study used a 30-nm x-ray beam to investigate the spatially resolved properties of a SmNiO3-based nanodevice doped with protons. It was found that regions with high proton concentration led to partial reduction of nickel valence, resulting in insulating behavior. The results indicate that proton doping modifies electronic valency rather than crystal lattice.