Critical fields and fundamental lengths in a superconducting electron-doped ${\mathrm{Pr}}_{1.85}$${\mathrm{Ce}}_{0.15}$${\mathrm{CuO}}_{4\mathrm{-}\mathit{y}}$ single crystal

Both critical fields ${\mathit{H}}_{\mathit{c}1}$ and ${\mathit{H}}_{\mathit{c}2}$, together with the intrinsic superconducting parameters λ and ξ, have been obtained from a set of careful systematic measurements of isothermal magnetization curves in a ${\mathrm{Pr}}_{1.85}$ ${\mathrm{Ce}}_{0.15}$ ${\mathrm{CuO}}_{4\mathrm{-}\mathit{y}}$ single crystal with H∥c. The analysis of the low-field regime has been performed, taking into account demagnetizing effects. A zone of complete diamagnetic screening is observed, followed by a transition region in which magnetic-flux penetration starts according to the predictions of Bean’s critical-state model. The ${\mathit{H}}_{\mathit{c}2}$(T) values, as well as a κ≤10, have been obtained from the reversible part of the magnetization curve, in the high-field region, by using Abrikosov’s model. The estimated values at T=0 K for the different intrinsic superconducting parameters are ${\mathit{H}}_{\mathit{c}1}$(0)≊920 Oe, ${\mathit{H}}_{\mathit{c}2}$(0)≊70 kOe, ${\lambda }_{\mathit{a}\mathit{b}}$(0)≊700 Å, and ${\xi }_{\mathit{a}\mathit{b}}$(0)≊70 Å. The significance of these intrinsic superconducting parameters, the rather low κ value, and a large Sommerfeld constant are discussed and compared with the corresponding values of other cuprates.