We report measurements of the magnetoresistance of ${\mathrm{Nd}}_{1.85}$${\mathrm{Ce}}_{0.15}$${\mathrm{CuO}}_{4\pm \mathrm{\delta }}$ epitaxial thin films with varying oxygen content in magnetic fields H applied parallel (H∥c) and perpendicular (H⊥c) to the tetragonal c axis. We have observed critical scaling of the electrical resistivity that is consistent with a vortex-glass transition for a film with an optimum superconducting transition temperature ${\mathit{T}}_{\mathit{c}}$ of ≊22 K and H∥c . The values of the zero-temperature upper critical field ${\mathit{H}}_{{\mathit{c}}_2}$(0)=80 kOe and the in-plane zero-temperature coherence length ${\xi }_{\mathit{ab}}$(0)=64 Å were obtained from an analysis of the fluctuation conductivity. For an overoxygenated film with ${\mathit{T}}_{\mathit{c}}$≊10 K, an anomaly develops with increasing field for H∥c and T≲2 K that is characterized by a minimum in the temperature dependence of the resistivity followed by a second resistive transition at a lower temperature, which is nearly independent of H. This behavior is similar to that previously observed in ${\mathrm{Nd}}_{2\mathrm{-}\mathit{x}}$${\mathrm{Ce}}_{\mathit{x}}$${\mathrm{CuO}}_{4\mathrm{-}\mathrm{\delta }}$ single crystals and may be associated with the magnetic ordering of the ${\mathrm{Nd}}^{3+}$ ions. © 1996 The American Physical Society.

• Received 16 April 1996

DOI:https://doi.org/10.1103/PhysRevB.54.3610