Upper critical field anisotropy in BaFe2-xCoxAs2 single crystals synthesized without flux

作者：Vinod K; Satya A T; Sharma Shilpam; Sundar C S; Bharathi A^*

来源：Physical Review B, 2011, 84(1): 012502.

DOI：10.1103/PhysRevB.84.012502

The upper critical field was measured up to 12 T for three BaFe2-xCoxAs2 single crystals with estimated Co concentrations of x = 0.082, x = 0.117, and x = 0.143. H-C2 versus temperature was measured from temperature-dependent resistivity for various applied magnetic fields, H parallel to ab and H parallel to c. The [dH(C2)/dT](T=Tc), normalized with the corresponding T-C, decreases with increasing Co content for both directions. The anisotropy gamma, defined as H-C2 parallel to ab/H-C2 parallel to c, shows a distinct increase with Co content, and its temperature dependence shows a peak close to the TC. Magnet-Transport measurements in the spin-density wave region of the x = 0.082 sample, showed negative and positive magneto-resistance reaspectively, for H parallel to ab and H square c. The implications of these results are discussed.

• 出版日期2011-7-13