Low-field magnetoresistance effect in core-shell structured La(0.7) Sr(0.3) CoO(3) nanoparticles.

Core-shell structured La(0.7) Sr(0.3) CoO(3) nanoparticles are synthesized and their magnetic and magneto-transport properties are investigated. In these core-shell La(0.7) Sr(0.3) CoO(3) nanoparticles, the cores are single-crystalline and ferromagnetic, whereas the shells are noncrystalline and predominantly paramagnetic. Moreover, the insulating-like shells can serve as a good spin tunneling barrier. Therefore, in such a special core-shell structure, the spin-polarized interparticle tunneling is improved due to the existence of shells, which thus induces an enhanced low-field magnetoresistance effect.