We report a systematic study of the normal-state Nernst effect in the electron-doped cuprates ${\mathrm{Pr}}_{2-x}{\mathrm{Ce}}_x\mathrm{Cu}{\mathrm{O}}_{4-\delta }$ over a wide range of doping $(0.05⩽x⩽0.21)$ and temperature. At low temperatures, we observed a notable vortex Nernst signal above $T_c$ in the underdoped films, but no such normal-state vortex Nernst signal is found in the overdoped region. The superconducting fluctuations in the underdoped region are most likely incoherent phase fluctuations as found in hole-doped cuprates. At high temperatures, a large normal-state Nernst signal is found at dopings from slightly underdoped to highly overdoped. Combined with normal-state thermoelectric power, Hall effect, and magnetoresistance measurements, the large Nernst effect is compatible with the two-band model. For the highly overdoped films, the large Nernst effect is anomalous and not explainable with the simple holelike Fermi surface seen in photoemission experiments.

• Received 7 August 2007

DOI:https://doi.org/10.1103/PhysRevB.76.174512