Large exchange bias in Cr substituted Fe(3)O(4) nanoparticles with FeO subdomains

Tuning the anisotropy through exchange bias in bimagnetic nanoparticles is an active research strategy for enhancing and tailoring the magnetic properties for a wide range of applications. Here we present a structural and magnetic characterization of unique FeCr-oxide nanoparticles generated from seed material with a Fe : Cr ratio of 4.71 : 1 using a physical aerosol method based on spark ablation. The nanoparticles have a novel bimagnetic structure composed of a 40 nm ferrimagnetic Cr-substituted Fe(3)O(4) structure with 4 nm antiferromagnetic Fe(x)O subdomains. Cooling in an applied magnetic field across the Néel temperature of the Fe(x)O subdomains results in a significant shift in the hysteresis, demonstrating the presence of a large exchange bias. The observed shift of μ(0)H(E) = 460 mT is among the largest values reported for Fe(x)O–Fe(3)O(4)-based nanoparticles and is attributed to the large antiferromagnetic-ferrimagnetic interface area provided by the subdomains.