Transport and anisotropy in single-crystalline SrFe2As2 and A0.6K0.4Fe2As2 ( A=Sr , Ba) superconductors
Abstract
We have successfully grown high-quality single crystals of SrFe2As2 and A0.6K0.4Fe2As2 ( A=Sr , Ba) using flux method. The resistivity, specific heat, and Hall coefficient have been measured. For parent compound SrFe2As2 , an anisotropic resistivity with ρc/ρab as large as 130 is obtained at low temperatures. A sharp drop in both in-plane and out-plane resistivities due to the spin-density-wave (SDW) instability is observed below 200 K. The angular dependence of in-plane magnetoresistance shows twofold 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 A0.6K0.4Fe2As2 ( A=Sr , Ba), the SDW instability is suppressed and the superconductivity appears with Tc above 35 K. The rather low anisotropy in upper critical field between H∥ab and H∥c indicates that interplane coupling plays an important role in hole-doped Fe-based superconductors.
- Publication:
-
Physical Review B
- Pub Date:
- December 2008
- DOI:
- 10.1103/PhysRevB.78.224512
- arXiv:
- arXiv:0806.2648
- Bibcode:
- 2008PhRvB..78v4512C
- Keywords:
-
- 74.70.-b;
- 74.62.Bf;
- 74.25.Gz;
- Superconducting materials;
- Effects of material synthesis crystal structure and chemical composition;
- Optical properties;
- Condensed Matter - Superconductivity;
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- 12 pages, 6 figures. Accepted by Phys. Rev. B