Controlling dual Mott states by hydrogen doping to perovskite rare-earth nickelates
Ikuya Matsuzawa, T. Ozawa, Yusuke Nishiya, Umar Sidik, Azusa N. Hattori, Hidekazu Tanaka, Katsuyuki Fukutani
Abstract
Doping hydrogen in correlated oxides is a promising way to control the materials functionalities. With in situ measurements of the resistance and hydrogen concentration by a nuclear reaction analysis, we have derived the detailed relation between the resistance and hydrogen concentration ($x$) for $R{\mathrm{NiO}}_{3}{\mathrm{H}}_{x}$ ($R=\text{Sm}$, Nd, and La), which reveal a clear resistance jump at a certain concentration. Taking account of the spatial distribution of hydrogen in both in-plane and depth directions, we have clarified that an insulating state is realized at $x=0.5$ and another insulating state is formed at $x=1$. The electronic mechanisms for the two states are proposed in terms of Mott phases.