The superconducting resistive transition of the layer compound Nb${\mathrm{Se}}_2$ has been observed for crystals a few layers thick. The $T_c$ decreases as the crystal thickness is reduced below six Nb${\mathrm{Se}}_2$ layers, and a $T_c$ of 3.8°K is predicted for a single layer. No significant increase in the transition width is observed as the number of Nb${\mathrm{Se}}_2$ layers is reduced. The results are compared to recent work on intercalated layer compounds.

• Received 7 December 1971

DOI:https://doi.org/10.1103/PhysRevLett.28.299