paper

Transport and anisotropy in single-crystalline SrFe $_{2}$ As $_{2}$ and $A_{0.6}$ K $_{0.4}$ Fe $_{2}$ As $_{2}$ ( $A$ = Sr, Ba) superconductors

arXiv:0806.2648 · doi:10.1103/PhysRevB.78.224512

Abstract

We have successfully grown high quality single crystals of SrFe $_{2}$ As $_{2}$ and A $_{0.6}$ K $_{0.4}$ Fe $_{2}$ As $_{2}$ (A=Sr, Ba) using flux method. The resistivity, specific heat and Hall coefficient have been measured. For parent compound SrFe $_{2}$ As $_{2}$ , an anisotropic resistivity with $I ¨ _{c}$ / $I ¨ _{ab}$ as large as 130 is obtained at low temperatures. A sharp drop in both in-plane and out-plane resistivity due to the SDW instability is observed below 200 K. The angular dependence of in-plane magnetoresistance shows 2-fold symmetry with field rotating within ab plane below SDW transition temperature. This is consistent with a stripe-type spin ordering in SDW state. In K doped A $_{0.6}$ K $_{0.4}$ Fe $_{2}$ As $_{2}$ (A=Sr. Ba), the SDW instability is suppressed and the superconductivity appears with T $_{c}$ above 35 K. The rather low anisotropy in upper critical field between H $∥$ ab and H $∥$ c indicates inter-plane coupling play an important role in hole doped Fe-based superconductors.

12 pages, 6 figures. Accepted by Phys. Rev. B

Transport and anisotropy in single-crystalline SrFe2​As2​ and A0.6​K0.4​Fe2​As2​ (A = Sr, Ba) superconductors

Abstract

Transport and anisotropy in single-crystalline SrFe $_{2}$ As $_{2}$ and $A_{0.6}$ K $_{0.4}$ Fe $_{2}$ As $_{2}$ ( $A$ = Sr, Ba) superconductors