Abnormal magnetoresistance effect in self-dopedAg2+δTethin films(δ<~0.25)

We report an abnormal room-temperature magnetoresistance behavior in self-doped ${\mathrm{Ag}}_{2+\delta }\mathrm{Te}$ films with Ag doping concentration $\delta <~\mathrm{0.25.}$ Both positive magnetoresistance and negative magnetoresistance are found with the magnetic field applied along perpendicular to the sample surface and opposite direction, respectively. It is also evident from our study that such magnetoresistance (MR) behavior is strongly dependent on the doping concentration δ and the annealing time. The origin of the MR behavior is discussed and tentatively ascribed to the complex structure of the films, which is analyzed by x-ray measurement.