Anomalies of Hall effect and magnetoresistance in oxygen deficient La2/3A1/3MnO3-δ epitaxial layers

The effect of oxygen disorder on the magnetic moment, resistivity, Hall effect and magnetoresistance of oxygen deficient La(2/3)A(1/3)MnO(3-delta) epitaxial thin films has been studied in magnetic fields up to 20 T and temperatures down to 4.2 K. Our results show, that rho(T, H) of these thin films depends on delta but differs in detail from that of equivalent nonstoichiometric bulk samples. In particular, changes in sign and magnitude of the magnetoresistance Delta rho/rho occur which suggest positive and negative shifts of a magnetic order-oder transition temperature in a magnetic field, dT(1)/dH, depending on delta. The Hall measurements give a hole carrier concentration of about 3 x 10(21) cm(-3) for near stoichiometric compounds.