Magnetoresistance anomaly in a resistive switching system*

Application of a strong electric stimulus, voltage or current, to the ferromagnetic oxide (La,Sr)MnO₃ (LSMO) triggers the intrinsic metal-insulator transition producing a volatile switching from a low- to high-resistance state. This resistive switching occurs in a characteristic spatial pattern, the formation of a paramagnetic insulating barrier perpendicular to the current flow, in contrast to the conventional filamentary percolation parallel to the current. We explored the evolution of anisotropic and colossal magnetoresistance in LSMO devices as they undergo resistive switching. We found that the magnetoresistance magnitude can be increased severalfold by initiating the switching and inducing the formation of a paramagnetic barrier inside the device. Moreover, by driving the LSMO device through the resistive switching the sign of magnetoresistance can be flipped from positive to negative and vice versa. Our results demonstrate the potential use of resistive switching in magnetic materials for novel spintronic applications.