Effect of Co doping and hydrostatic pressure on SrFe2As2

E. Lengyel; M. Kumar; W. Schnelle; A. Leithe-Jasper; M. Nicklas

doi:10.1002/pssb.201600154

paper

Effect of Co doping and hydrostatic pressure on SrFe2As2

arXiv:1611.08447 · doi:10.1002/pssb.201600154

Abstract

We report a pressure study on electron doped SrFe $_{2 - x}$ Co $_{x}$ As $_{2}$ by electrical-resistivity ( $I ¨ $ ) and magnetic-susceptibility ( $I ¨ $ ) experiments. Application of either external pressure or Co substitution rapidly suppresses the spin-density wave ordering of the Fe moments and induces superconductivity in SrFe $_{2}$ As $_{2}$ . At $x = 0.2$ the broad superconducting (SC) dome in the $T - p$ phase diagram exhibits its maximum $T_{c, max} = 20$ K at a pressure of only $p_{max} \approx 0.75$ GPa. In SrFe $_{1.5}$ Co $_{0.5}$ As $_{2}$ no superconductivity is observed anymore up to 2.8 GPa. Upon increasing the Co concentration the maximum of the SC dome shifts toward lower pressure accompanied by a decrease in the value of $T_{c, max}$ . Even though, superconductivity is induced by both tuning methods, Co substitution leads to a much more robust SC state. Our study evidences that in SrFe $_{2 - x}$ Co $_{x}$ As $_{2}$ both, the effect of pressure and Co-substitution, have to be considered in order to understand the SC phase-diagram and further attests the close relationship of SrFe $_{2}$ As $_{2}$ and its sister compound BaFe $_{2}$ As $_{2}$ .

6 pages, 6 figures