Exchange bias effect involved with tunneling magnetoresistance in polycrystalline La_{0.88}Sr_{0.12}CoO_3

TL;DR

This paper reports the observation of exchange bias and tunneling magnetoresistance in polycrystalline La_{0.88}Sr_{0.12}CoO_3, revealing novel magnetic effects in a bulk compound relevant for spintronic applications.

Contribution

First demonstration of exchange bias effect coupled with tunneling magnetoresistance in a polycrystalline cobaltite compound, highlighting intragranular interface effects.

Findings

Exchange bias observed in MR-H curves after field cooling.

Training effect in MR shift explained by spin relaxation.

Strong field-cooled effects in resistivity below spin freezing temperature.

Abstract

We report the exchange bias (EB) effect along with tunneling magnetoresistance (MR) in polycrystalline La_{0.88}Sr_{0.12}CoO_3. Analogous to the shift in the magnetic hysteresis loop along the field (H)-axis a shift is clearly observed in the MR-H curve when the sample is cooled in a static magnetic field. Training effect (TE) is a significant manifestation of EB effect which describes the decrease of EB effect when sample is successively field-cycled at a particular temperature. We observe TE in the shift of the MR-H curve which could be interpreted by the spin configurational relaxation model. A strong field-cooled (FC) effect in the temperature as well as time dependence of resistivity is observed below spin freezing temperature. The unusual MR results measured in FC mode are interpreted in terms of intragranular interface effect between short range ferromagnetic clusters and spin-glass matrix giving rise to the EB effect. EB effect in MR has been observed in bilayer or multilayer films which has not yet seen in a polycrystalline compound. EB effect involved with tunneling MR and semiconducting transport property attributed to the intragranular intrinsic nanostructure is promising for the spintronic applications.