title: Multiband superconductivity of heavy electrons in a TlNi2Se2 single crystal.
abstract: We have made the first observation of superconductivity in TlNi2Se2 at T(C)=3.7  K, and it appears to involve heavy electrons with an effective mass m*=(14-20)m(b), as inferred from the normal-state electronic specific heat and the upper critical field, H(C2)(T). We found that the zero-field electronic specific-heat data, C(es)(T) (0.5  K≤T<3.7  K) in the superconducting state can be fitted with a two-gap BCS model, indicating that TlNi2Se2 seems to be a multiband superconductor, which is consistent with the band calculation for the isostructural KNi2S2. It is also found that the electronic specific-heat coefficient in the mixed state γN(H) exhibits a H(1/2) behavior, which is considered as a common feature of the d-wave superconductors. TlNi2Se2, as a d-electron system with heavy electron superconductivity, may be a bridge between cuprate- or iron-based and conventional heavy-fermion superconductors.
authors.affiliation: Department of Physics, Zhejiang University, Hangzhou 310027, China and Department of Physics, Hangzhou Normal University, Hangzhou 310036, China.
authors.forename: Hangdong
authors.initials: H
authors.lastname: Wang
authors.forename: Chiheng
authors.initials: C
authors.lastname: Dong
authors.forename: Qianhui
authors.initials: Q
authors.lastname: Mao
authors.forename: Rajwali
authors.initials: R
authors.lastname: Khan
authors.forename: Xi
authors.initials: X
authors.lastname: Zhou
authors.forename: Chenxia
authors.initials: C
authors.lastname: Li
authors.forename: Bin
authors.initials: B
authors.lastname: Chen
authors.forename: Jinhu
authors.initials: J
authors.lastname: Yang
authors.forename: Qiping
authors.initials: Q
authors.lastname: Su
authors.forename: Minghu
authors.initials: M
authors.lastname: Fang