Resistance control of a magnetoresistive manganite by spin-injection

TL;DR

This paper demonstrates a novel spin-injection effect in a manganite, where spin-polarized current induces ferromagnetism and increases conductivity in a locally irradiated paramagnetic region, revealing new control mechanisms for magnetic states.

Contribution

The study introduces a new spin-injection phenomenon in manganites with a specially fabricated structure, showing control over magnetic and electronic properties via spin-polarized current.

Findings

Spin-polarized current induces ferromagnetism in a paramagnetic manganite region.

Irradiation creates a ferromagnetic/paramagnetic/ferromagnetic structure.

Injected spins suppress spin fluctuations, increasing conductivity.

Abstract

We report a new 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 central part was subsequently irradiated with Ga+ ions lightly. 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 injected spins.