Quantum oscillations in the SmFeAsO parent compound and superconducting SmFeAs(O,F)

By carrying out magnetotransport measurements up to 30 T, we succeeded in detecting and analyzing quantitatively Shubnikov--de Haas oscillations in two crystals of the $RE\mathrm{FeAsO}$ ($RE=\mathrm{rare}\phantom{\rule{0.28em}{0ex}}\mathrm{earth}$) family of iron pnictides, namely, the undoped SmFeAsO and the superconducting fluorine underdoped SmFeAs(O,F). We combine experimental outcomes and ab initio calculations of electronic structure to get the following direct evidences: (i) the Shubnikov--de Haas oscillations are determined by a two-dimensional hole band, whose effective mass is ${m}^{*}=(0.50\ifmmode\pm\else\textpm\fi{}0.1)\phantom{\rule{0.16em}{0ex}}{m}_{e}$ in the undoped sample and ${m}^{*}=(0.89\ifmmode\pm\else\textpm\fi{}0.1)\phantom{\rule{0.16em}{0ex}}{m}_{e}$ in the F-doped sample, while classical magnetotransport is dominated by an electron band; (ii) in the superconducting compound we give a quantitative account of the low effectiveness of electron doping associated with fluorine substitution.