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\bibitem{Clima_etal2014} {\textquotedblleft}\textit{HfO$_{x}$ as RRAM material : first principles insights on the working principles}{\textquotedblright}. Clima S, Govoreanu B, Jurczak M, Pourtois G, Microelectronic engineering \textbf{120}, 13 (2014).   http://doi.org/10.1016/j.mee.2013.08.002

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