Structural, magnetic, and electronic transport properties of hole-doped SrFe2−xCuxAs2single crystals

Abstract

We report the structural, magnetic, and electronic transport properties of SrFe${}_{2\ensuremath{-}x}$Cu${}_{x}$As${}_{2}$ single crystals grown by a self-flux technique. Both SrCu${}_{2}$As${}_{2}$ and SrFe${}_{2}$As${}_{2}$ crystallize in a ThCr${}_{2}$Si${}_{2}$-type (122-type) structure at room temperature, but exhibit distinct magnetic and electronic transport properties. According to the x-ray photoelectron spectroscopy Cu $2p$ core line position, resistivity, susceptibility, and positive Hall coefficient, SrCu${}_{2}$As${}_{2}$ is an $\mathit{sp}$-band metal with Cu in the 3d${}^{10}$ electronic configuration corresponding to the valence state Cu${}^{1+}$. Compared with SrCu${}_{2}$As${}_{2}$, the almost unchanged Cu $2p$ core line position in SrFe${}_{2\ensuremath{-}x}$Cu${}_{x}$As${}_{2}$ indicates that partial Cu substitutions for Fe in SrFe${}_{2}$As${}_{2}$ may result in hole doping rather than the expected electron doping. No superconductivity is induced by Cu substitution on Fe sites, even though the structural/spin density wave transition is gradually suppressed with increasing Cu doping.