Control of resistance of a magnetoresistive manganite by spin injection

We report a spin-injection effect found for a manganite using a specially fabricated sample. A wire of La0.7Sr0.3MnO3 was patterned by means of focused ion beam etching, and the center was subsequently lightly irradiated with Ga+ ions. The ferromagnetic Curie temperature was reduced locally by the irradiation from TC to TC′, and thus a sequential ferromagnetic/paramagnetic/ferromagnetic structure was realized along the wire between TC and TC′. The injection of spin-polarized current from the ferromagnetic manganite into the paramagnetic part rendered the latter ferromagnetic and more conductive. This can be explained by assuming the suppression of spin fluctuation in the paramagnet by the spins injected.