Superconductivity at 32K and anisotropy in Tl0.58Rb0.42Fe1.72Se2 crystals

Tl0.58Rb0.42Fe1.72Se2 single crystals were successfully synthesized with the Bridgeman method. The physical properties are characterized by electrical resistivity, magnetization and Hall resistivity. Tl0.58Rb0.42Fe1.72Se2 undergoes a superconducting transition at T-c(onset) = 32K and T-c(zero) = 31.4K. Extrapolation of the upper critical field H-c2 at T-c to zero temperature gives a large value of H-c2(0) (H-c2(0) = 221T for H parallel to ab and H-c2(0) = 44.2T for H parallel to c). The Hall coefficient changes sign upon cooling down, indicating a possible multi-band behavior. The normal-state magnetic susceptibility decreases with decreasing temperature, suggesting strong antiferromagnetic (AFM) spin fluctuations, which might be related to the superconductivity (SC). Copyright (C) EPLA, 2011