Influence of doping level on the Hall coefficient and on the thermoelectric power in Nd_(2-x)Ce_xCuO₄

Hall coefficient $R_H$ and thermoelectric power TEP are studied systematically in the single crystals $Nd_{2-x}Ce_xCuO_{4+\delta}$ (NCCO) with different x from underdoped to overdoped regime. With increasing doping level, both $R_H$ and TEP decrease and change their sign from negative to positive. A striking feature is that the temperature dependence of the Hall angle follows a $T^4$ behavior in the underdoped regime, while a $T^2$ in the overdoped regime. These behaviors are closely related to the evolution of Fermi surface with doping level observed by ARPES.