Upper Critical Fields of the 11-System Iron-Chalcogenide Superconductor FeSe0.25Te0.75

作者：Kida Takanori^*; Matsunaga Takahiro; Hagiwara Masayuki; Mizuguchi Yoshikazu; Takano Yoshihiko; Kindo Koichi

来源：Journal of the Physical Society of Japan, 2009, 78(11): 113701.

DOI：10.1143/JPSJ.78.113701

• iron-based superconductor
• FeSe
• magnetoresistance
• upper critical field

We have performed electrical resistivity measurements of a polycrystalline sample of FeSe0.25Te0.75, which exhibits superconductivity at T-c similar to 14 K, in magnetic fields up to 55 T to determine the upper critical field mu H-0(c2). In this compound, very large slopes of mu H-0(c2) at the onset, the mid-point, the zero-resistivity temperatures on superconductivity are determined to be -13.7, -10.1, and -6.9T/K, respectively. The observed mu H-0(c2)(T)s of this compound are considerably smaller than those expected from the Werthamer-Helfand-Hohenberg model, manifesting the Pauli limiting behavior. These results suggest that this compound shows the spin-ringlet pairing in the superconducting state.

• 出版日期2009-11