Exchange bias effect involved with tunneling magnetoresistance in polycrystalline La_0.88Sr_0.12CoO₃

Department of Solid State Physics, Indian Association for the Cultivation of Science Jadavpur, Kolkata 700 032, India

Corresponding author: sspsg2@iacs.res.in

Received: 10 June 2009
Accepted: 20 August 2009

Abstract

We report the exchange bias (EB) effect along with tunneling magnetoresistance (MR) in polycrystalline La_0.88Sr_0.12CoO₃. 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.