High-temperature resistivity in the iron pnictides and the electron-doped cuprates

Abstract

We measured the high-temperature (up to $800$ K) resistivity of several dopings of SrFe${}_{2\ensuremath{-}x}$(Ni,Co)${}_{x}$As${}_{2}$ (Sr-122) and compared the results with similar measurements on electron-doped cuprates. We find that the Sr-122 pnictide resistivity saturates above $500$ K at around 400--700 $\mathrm{\ensuremath{\mu}}\mathrm{\ensuremath{\Omega}} $cm, consistent with the Mott-Ioffe-Regel (MIR) limit and in contrast with the MIR-violating behavior of the hole-doped cuprates and our measurements on electron-doped cuprates. This supports the view that electronic correlations in the ferropnictides may be weaker than in the cuprates.