Resistivity and hall effect in single-crystal films of Nd2-xCexCuO4+delta with different oxygen contents

The temperature dependences of resistivity rho(ab)(T) (1.5 less than or equal to T less than or equal to 300 K) of single-crystal Nd2-xCexO4+delta films (0 less than or equal to x less than or equal to 0.20) with different oxygen contents (delta) were investigated for each value of x. It was established that for all Ce concentrations an increase in the content of oxygen results in a substantial (by one-two orders of magnitude) increase in the resistivity in the whole temperature range, which corresponds to an increase in the degree of disorder in the system (a decrease in the parameter k(F)l). From measurements of the Hall effect R-H at T = 77 K, it was established that in the samples with x = 0.12 and 0.15 the majority carriers are electrons (R-H < 0), whose concentration remains unchanged upon the variation of the annealing regime; i.e., the decrease in k(F)l with increasing concentration of nonstoichiometric oxygen defects is related to a decrease in the mean free path of electrons. R-H is also negative in the samples with x = 0.17, but the value of vertical bar R-H vertical bar in this case is by an order of magnitude smaller than in the samples with x = 0.12 and x = 0.15. This is probably related to the appearance of a second type of carrier-holes. In the samples with x = 0.20, R-H > 0; i.e., the contribution of holes to conductivity is dominant.