Thermoinduced magnetic moment in akaganeite nanoparticles.

Thermoinduced magnetic moment in akaganeite nanoparticles.

It is shown that akaganeite beta-FeOOH provides a good model material to experimentally investigate thermoinduced magnetic moments in antiferromagnetic nanoparticles. We characterize the magnetic properties, exchange field, anisotropy field, and antiferromagnetic susceptibility of bulk akaganeite. In the nanoparticles, we find a drastic enhancement of the antiferromagnetic susceptibility, a phenomenon first predicted by Neel. Also, we find that akaganeite nanoparticles possess a thermoinduced magnetic moment.