We show that antiferromagnetic susceptibility in ferritin increases with temperature between 4.2 K and 180 K (i. e. below the N\'{e}el temperature) when taken as the derivative of the magnetization at high fields (30×104 Oe). This behavior contrasts with the decrease in temperature previously found, where the susceptibility was determined at lower fields (5×104 Oe). At high fields (up to 50×104 Oe) the temperature dependence of the antiferromagnetic susceptibility in ferritin nanoparticles approaches the normal behavior of bulk antiferromagnets and nanoparticles considering superantiferromagnetism, this latter leading to a better agreement at high field and low temperature. The contrast with the previous results is due to the insufficient field range used (<5×104 Oe), not enough to saturate the ferritin uncompensated moment.
@article{arxiv.0902.0929,
title = {Temperature dependence of antiferromagnetic susceptibility in ferritin},
author = {N. J. O. Silva and A. Millan and F. Palacio and E. Kampert and U. Zeitler and H. Rakoto and V. S. Amaral},
journal= {arXiv preprint arXiv:0902.0929},
year = {2009}
}