Low-temperature Hall effect in electron-doped superconducting La_2−xCe_xCuO₄ thin films

We investigate the low-temperature Hall effect in electron-doped La_2−xCe_xCuO₄ thin films from heavily underdoped x=0.06 to heavily overdoped x=0.17. With increasing x, the charge carriers that dominate the Hall effect gradually change from electronlike to holelike. From the Hall coefficient and differential Hall coefficient, we infer that a large holelike Fermi surface forms above x=0.15, that is, the electronlike pocket may exist until x=0.15. Meanwhile, the sign of the Hall resistivity changes from negative (x=0.105) to positive (x=0.12) at 2 K, indicating that single electron pocket exists below x=0.105 at low temperature.