Superconductivity in a misfit compound (PbSe)1.12(TaSe2)

Abstract

We report the discovery of superconductivity with a maximum Tc ≈ 1.28 K in Br-doped (PbSe)1.12(TaSe2), which is a new misfit compound consisting of alternating layers of distorted rocksalt PbSe and dichalcogenide TaSe2. It is found that the Br-doping is required for the formation of this misfit compound and superconductivity can be tuned by the Br content. The large anisotropic parameter of resistivity ≈ 100 and that of the upper critical field = ≈ 10 are obtained. The estimated c-axis coherence length ≈ 6.3 nm, larger than the c-axis lattice constant, which implies that this compound is an anisotropic three-dimensional superconductor. The Hall coefficient measurements suggest that the charge transport is dominated by the hole-type charge carrier and there is a charge transfer from the PbSe layer to the conducting TaSe2 layer. The small normalized specific heat jump ΔC/γ Tc = 1.16 and electron–phonon coupling constant λep ≈ 0.61 indicate that Br-doped (PbSe)1.12(TaSe2) is a weak coupling Bardeen–Cooper–Schrieffer superconductor.