Enhanced superconductivity in a misfit compound (PbSe)1.12 (TaSe2)2 with double TaSe2 layers

Abstract

We report the discovery of superconductivity with a maximum Tc ≈ 1.85 K in a new misfit layered compound , which consists of alternating layers of a distorted rocksalt layer PbSe and a double-layer dichalcogenide . A large anisotropic parameter of resistivity and that of the upper critical field = are obtained. The estimated c-axis coherence length is comparable to the c-axis lattice constant. Moreover, the estimated upper critical field , significantly exceeding the Pauli paramagnetic limit. All these data indicate a quasi-two-dimensional nature of the superconducting properties in . Compared with the physical properties of the misfit compound superconductor with only the half-layer of the unit, our study suggests that the enhancement of Tc in with double TaSe2 layers is presumably related to the increase in hole carrier density. The reduced charge transfer from the PbSe layer to the conducting TaSe2 layer could account for the variation in the charge carrier density.