We report ac susceptibility, electrical resistivity, and structural measurements on crystalline ${\mathrm{Pr}}_{2\mathrm{-}\mathrm{x}}$${\mathrm{Ce}}_{\mathrm{x}}$${\mathrm{CuO}}_{4\mathrm{-}\mathrm{y}}$ (PCCO) thin films prepared by pulsed laser deposition. We find superconductivity occurs within a narrow Ce concentration range (0.1374, 4927 (1995)] on PCCO single crystals where superconductivity near 20 K was found for Ce concentration as low as x=0.04. Possible reasons for this difference will be discussed.

• Received 19 August 1996

DOI:https://doi.org/10.1103/PhysRevB.55.R6145