Hole superconductivity in the electron-doped superconductor PCCO

We measure the resistivity and Hall angle of the electron-doped superconductor Pr_{2-x}Ce_xCuO_4 as a function of doping and temperature. The resistivity Rho_xx at temperatures 100K < T < 300K is mostly sensitive to the electrons. Its temperature behavior is doping independent over a wide doping range and even for non superconducting samples. On the other hand,the transverse resistivity rho_xy, or the Hall angle theta_H where cot(theta_H) = rho_xx/rho_xy, is sensitive to both holes and electrons. Its temperature dependence is strongly influenced by doping, and cot(theta_H) can be used to identify optimum doping (the maximum Tc) even well above the critical temperature. These results lead to a conclusion that in electron doped cuprates holes are responsible for the superconductivity.