Fe-based superconductivity with Tc = 31 K bordering an antiferromagnetic insulator in (TI,K) FexSe2
Department of Physics, Zhejiang University - Hangzhou 310027, China
2 Department of Physics, Hangzhou Normal University - Hangzhou 310036, China
Accepted: 21 March 2011
(Tl,K)FexSe2 single crystals were first successfully synthesized with the Bridgeman method. The physical properties are characterized by electrical resistivity, magnetic susceptibility and Hall coefficient. We found that the (Tl,K)FexSe2 (1.30 ≤ x ≤ 1.65) compounds show an antiferromagetic (AFM) insulator behavior, which may be associated with the Fe-vacancy ordering in the crystals. While in the 1.70 ≤ x < 1.78 crystals, superconductivity (SC) coexists with an insulating phase. As Fe content further increases, the bulk SC with Tc = 31 K (and a Tconset as high as 40 K) appears in the 1.78 ≤ x ≤ 1.88 crystals. Our discovery represents the first Fe-based high-temperature superconductivity (HTSC) at the verge of an AFM insulator.
PACS: 74.62.Bf – Effects of material synthesis, crystal structure, and chemical composition / 74.25.F- – Transport properties / 74.25.Ha – Magnetic properties including vortex structures and related phenomena
© EPLA, 2011