Transport and Raman signatures of electron-doped SmNiO$_{3}$ thin films

We report low temperature transport and Raman spectroscopy measurements of electron-doped SmNiO$_{3\, }$(SNO) thin films. It has been shown that pristine SNO films can be doped with electrons using hydrogen. Our transport measurements indicate a Coulomb interaction dominated variable range hopping (VRH) for electron-doped samples whereas the pristine films show a Mott type VRH mechanism at low temperatures. The electron-doped samples display a strong localization which can be correlated with the high spin state of Ni$^{2+}$ ions. The spatial Raman map shows a remarkable shift of about 167 cm$^{-1}$ with electron doping thus serving as a spectroscopic tool to investigate hydrogen in our films. \textbf{References} \begin{enumerate} \item J. Shi, Y. Zhou and S. Ramanathan, Nat. Commun \textbf{5}, 4860 (2014) \item Jikun Chen \textit{et al}., Appl. Phys. Lett. \textbf{107}, 031905 (2015) \end{enumerate}