Superconductivity in layered misfit chalcogenide BiSe-NbSe₂

Layered misfit chalcogenides, (BiSe)_1+d(NbSe₂) is an anisotropic superconductor (Tc=2.3 K)[1]. The superconductivity is mostly carried out in NbSe₂ layers, i.e. a superconducting NbSe₂ layer is sandwiched by insulating BiSe layers. The situation for NbSe₂ resembles the monolayer on a substrate, albeit the slight charge transfer is discussed from BiSe layers. We report the new structure of the series of the material, (BiSe)_1+d(NbSe₂)_n, and the enhancement of Tc as the number of NbSe₂ layers (n) increases.

[1] A. Nadar et al., Solid State Commun. 101, 149 (1997).