title: Superconductivity induced by Ni doping in SmFe(1-x)Ni(x)AsO.
abstract: Superconductivity with a T(c) of about 10 K is observed in the Ni-doped SmFe(1-x)Ni(x)AsO system. The measurements of resistivity and magnetic susceptibility show that the spin-density wave (SDW) order is quickly suppressed with increasing Ni content, and superconductivity emerges as x≥0.04. T(c)(mid) shows a maximum of 10.8 K at x = 0.06, and it drops to lower than 2 K as x>0.12. Meanwhile, the upper critical field (H(c2)(0)) is estimated to be about 40 T for the optimally-doped sample (x = 0.06). The normal state thermopower is negative for all the Ni-doped samples, indicating that an electron-type charge carrier dominates in the transport properties. Moreover, the magnitude of the room-temperature thermopower increases with increasing Ni content, and then shows a broad peak around x = 0.06. We found that there is an obvious correlation between the anomalously enhanced thermopower and superconductivity. A phase diagram is derived based on the transport measurements and a dome-like T(c)(x) curve is established.
authors.affiliation: Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China.
authors.forename: Y K
authors.initials: YK
authors.lastname: Li
authors.forename: X
authors.initials: X
authors.lastname: Lin
authors.forename: T
authors.initials: T
authors.lastname: Zhou
authors.forename: J Q
authors.initials: JQ
authors.lastname: Shen
authors.forename: Q
authors.initials: Q
authors.lastname: Tao
authors.forename: G H
authors.initials: GH
authors.lastname: Cao
authors.forename: Z A
authors.initials: ZA
authors.lastname: Xu